<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2023 Workiva-->
<!--r:e1f5e940-a531-4eaa-ab3b-95dc4ddb12f9,g:d5b47e48-7033-447d-8d0b-ac3aec4a0c82-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.instacart.com/role/CondensedConsolidatedBalanceSheets" xlink:type="simple" xlink:href="cart-20230930.xsd#CondensedConsolidatedBalanceSheets"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_ebe96598-a356-4b9c-b309-92b65a6c06a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ebe96598-a356-4b9c-b309-92b65a6c06a1" xlink:to="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_8506aabf-70ae-42ea-8ab6-be76dd011c5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_AssetsCurrentAbstract_8506aabf-70ae-42ea-8ab6-be76dd011c5d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_e1e63ecb-1bad-4972-94a8-e8f705642cc3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8506aabf-70ae-42ea-8ab6-be76dd011c5d" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_e1e63ecb-1bad-4972-94a8-e8f705642cc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesCurrent_98d0abd7-d41b-4279-8cf6-51db845c9fec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketableSecuritiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8506aabf-70ae-42ea-8ab6-be76dd011c5d" xlink:to="loc_us-gaap_MarketableSecuritiesCurrent_98d0abd7-d41b-4279-8cf6-51db845c9fec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_756513df-b49b-41cb-826a-851559602d3b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8506aabf-70ae-42ea-8ab6-be76dd011c5d" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_756513df-b49b-41cb-826a-851559602d3b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_b7f74916-a2b0-44fe-90e6-7b22036b37f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8506aabf-70ae-42ea-8ab6-be76dd011c5d" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_b7f74916-a2b0-44fe-90e6-7b22036b37f1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_d3b98645-1d4f-4a0f-b144-2e0c0bdf9022" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8506aabf-70ae-42ea-8ab6-be76dd011c5d" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_d3b98645-1d4f-4a0f-b144-2e0c0bdf9022" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_204c345a-2885-4c38-a2b6-04743dd8e1d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_8506aabf-70ae-42ea-8ab6-be76dd011c5d" xlink:to="loc_us-gaap_AssetsCurrent_204c345a-2885-4c38-a2b6-04743dd8e1d2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesNoncurrent_bcae345f-2c5b-42c6-8da1-07fb67bf4cdf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketableSecuritiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_MarketableSecuritiesNoncurrent_bcae345f-2c5b-42c6-8da1-07fb67bf4cdf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_f38fcc2e-8840-4fa1-a866-1651eee3e181" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashAndCashEquivalentsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_f38fcc2e-8840-4fa1-a866-1651eee3e181" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_b00b5f0e-8874-415f-957a-f35090ff8410" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_b00b5f0e-8874-415f-957a-f35090ff8410" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_f294813c-884c-4235-a542-c48ea7183e12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_f294813c-884c-4235-a542-c48ea7183e12" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_fd728650-3972-459e-bd81-d24808fb433a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_fd728650-3972-459e-bd81-d24808fb433a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_86bfdfb6-5ffa-49f0-a473-dbe56d0caa91" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_Goodwill_86bfdfb6-5ffa-49f0-a473-dbe56d0caa91" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_f5010e0d-3955-4568-baee-ada72600eb30" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_f5010e0d-3955-4568-baee-ada72600eb30" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_ed7cb4bc-b8f9-4387-aec9-fe8b60f67083" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_ed7cb4bc-b8f9-4387-aec9-fe8b60f67083" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_e55dd6f5-d00b-47ed-910f-32cd6462c4f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c1bec62-af60-452c-b9b0-d0497d77b66c" xlink:to="loc_us-gaap_Assets_e55dd6f5-d00b-47ed-910f-32cd6462c4f2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ebe96598-a356-4b9c-b309-92b65a6c06a1" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_6c705328-79a1-426c-b4ff-208636112687" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_6c705328-79a1-426c-b4ff-208636112687" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_33b04da1-01e5-46bf-ad2b-320bab529349" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_6c705328-79a1-426c-b4ff-208636112687" xlink:to="loc_us-gaap_AccountsPayableCurrent_33b04da1-01e5-46bf-ad2b-320bab529349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_67cc7779-5aa3-4d71-bd15-a0bdcc0a5bd6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_6c705328-79a1-426c-b4ff-208636112687" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_67cc7779-5aa3-4d71-bd15-a0bdcc0a5bd6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_ce40914a-fb2e-48e7-97e9-720ea805eddb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_6c705328-79a1-426c-b4ff-208636112687" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_ce40914a-fb2e-48e7-97e9-720ea805eddb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_d18a5c6b-15da-40c2-b43a-91f72522fbbd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_6c705328-79a1-426c-b4ff-208636112687" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_d18a5c6b-15da-40c2-b43a-91f72522fbbd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_91f8a36f-00a6-40bf-9dd4-7cd2dff08732" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_6c705328-79a1-426c-b4ff-208636112687" xlink:to="loc_us-gaap_LiabilitiesCurrent_91f8a36f-00a6-40bf-9dd4-7cd2dff08732" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_c4466c97-4661-4e62-8c5a-f06a1ae7b32e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_c4466c97-4661-4e62-8c5a-f06a1ae7b32e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_573e3d64-9830-4189-bf9d-63960430c9bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_573e3d64-9830-4189-bf9d-63960430c9bb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_e2a1efbf-52b0-4f9c-bbb7-8e9c748a4a90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:to="loc_us-gaap_Liabilities_e2a1efbf-52b0-4f9c-bbb7-8e9c748a4a90" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_48c1143a-057a-4443-b8db-182e1d38175d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:to="loc_us-gaap_CommitmentsAndContingencies_48c1143a-057a-4443-b8db-182e1d38175d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_f6ba48f4-5b20-43e7-8b29-529f6d5f4d67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_f6ba48f4-5b20-43e7-8b29-529f6d5f4d67" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_64bfaadf-7c9c-45b1-93bc-5258a7922bac" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_55221384-f18a-4cea-a643-063b8c827e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:to="loc_us-gaap_PreferredStockValue_55221384-f18a-4cea-a643-063b8c827e7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_7fd9cc99-a923-4385-8b60-0b77533cae66" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:to="loc_us-gaap_CommonStockValue_7fd9cc99-a923-4385-8b60-0b77533cae66" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableStockValueIssued_757a99be-d52b-45bb-ac85-feaaff4b7d10" xlink:href="cart-20230930.xsd#cart_ExchangeableStockValueIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:to="loc_cart_ExchangeableStockValueIssued_757a99be-d52b-45bb-ac85-feaaff4b7d10" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_1a962892-f086-4648-9b51-d4d7603d0c5e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:to="loc_us-gaap_AdditionalPaidInCapital_1a962892-f086-4648-9b51-d4d7603d0c5e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_792261de-9e26-454a-a19a-f329cce42bf6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_792261de-9e26-454a-a19a-f329cce42bf6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_94892e93-3780-43b0-8ef6-7abf81ad3056" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_94892e93-3780-43b0-8ef6-7abf81ad3056" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_e0db8da4-efa4-4b3a-86cd-f452074d33a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_aab466ec-7474-4b50-9916-bef69452e2a5" xlink:to="loc_us-gaap_StockholdersEquity_e0db8da4-efa4-4b3a-86cd-f452074d33a4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_679f3f48-5050-4f45-9858-d199287795b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ebe96598-a356-4b9c-b309-92b65a6c06a1" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_679f3f48-5050-4f45-9858-d199287795b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_7a0c0946-76c9-4d02-b2f6-3876a4406b90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_ebe96598-a356-4b9c-b309-92b65a6c06a1" xlink:to="loc_us-gaap_StatementTable_7a0c0946-76c9-4d02-b2f6-3876a4406b90" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_15299ee3-aeee-462c-af97-2963fb7e3d63" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7a0c0946-76c9-4d02-b2f6-3876a4406b90" xlink:to="loc_us-gaap_StatementClassOfStockAxis_15299ee3-aeee-462c-af97-2963fb7e3d63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_15299ee3-aeee-462c-af97-2963fb7e3d63_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_15299ee3-aeee-462c-af97-2963fb7e3d63" xlink:to="loc_us-gaap_ClassOfStockDomain_15299ee3-aeee-462c-af97-2963fb7e3d63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_1a8917c4-664e-446c-9269-012b9ab7204d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_15299ee3-aeee-462c-af97-2963fb7e3d63" xlink:to="loc_us-gaap_ClassOfStockDomain_1a8917c4-664e-446c-9269-012b9ab7204d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_15058a3b-f9e6-4b0e-a383-932946558706" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1a8917c4-664e-446c-9269-012b9ab7204d" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_15058a3b-f9e6-4b0e-a383-932946558706" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_95597daa-c38c-44f0-ba7b-9191e68f38b8" xlink:href="cart-20230930.xsd#cart_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1a8917c4-664e-446c-9269-012b9ab7204d" xlink:to="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_95597daa-c38c-44f0-ba7b-9191e68f38b8" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" xlink:href="cart-20230930.xsd#CondensedConsolidatedBalanceSheetsParenthetical"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_3199413f-50c1-4d0d-9450-78babec0f52c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_3199413f-50c1-4d0d-9450-78babec0f52c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_668bff14-1edb-4a96-ab63-a11c6db0f774" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_668bff14-1edb-4a96-ab63-a11c6db0f774" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesAuthorized_69007e02-c7f9-4fb5-ba1e-07adf0826f96" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_TemporaryEquitySharesAuthorized_69007e02-c7f9-4fb5-ba1e-07adf0826f96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued_d93f04ec-7540-4dce-88a2-3a62a07fbab9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued_d93f04ec-7540-4dce-88a2-3a62a07fbab9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_c9e03569-6485-4474-8152-34774e9f0987" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_c9e03569-6485-4474-8152-34774e9f0987" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityLiquidationPreference_1719afac-4fd1-4655-bda0-5b2d7a65bf4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityLiquidationPreference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_TemporaryEquityLiquidationPreference_1719afac-4fd1-4655-bda0-5b2d7a65bf4e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_6df766f5-8b2c-45b2-bc01-8c85d5998ffa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_6df766f5-8b2c-45b2-bc01-8c85d5998ffa" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_01c0d561-3bb7-440d-b25a-2c97d499c08a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_01c0d561-3bb7-440d-b25a-2c97d499c08a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_7d940b00-ae41-43af-bd60-4c82c965e4d3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_PreferredStockSharesIssued_7d940b00-ae41-43af-bd60-4c82c965e4d3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_e88730e6-58f1-4425-803c-548427e3cda9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_e88730e6-58f1-4425-803c-548427e3cda9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_b51da8ed-0595-4fc6-904a-9970221973df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_b51da8ed-0595-4fc6-904a-9970221973df" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_6ef0adbe-1303-485b-8773-9af4503e9923" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_6ef0adbe-1303-485b-8773-9af4503e9923" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_524ea2dc-46ab-4d49-ba30-3a5cb51fe98b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_CommonStockSharesIssued_524ea2dc-46ab-4d49-ba30-3a5cb51fe98b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_eb55417c-3675-415b-8963-d17c49bbec47" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_eb55417c-3675-415b-8963-d17c49bbec47" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableStockSharesAuthorized_3f63c846-dc6c-4b7a-a1ce-4cf7c1320a2c" xlink:href="cart-20230930.xsd#cart_ExchangeableStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_cart_ExchangeableStockSharesAuthorized_3f63c846-dc6c-4b7a-a1ce-4cf7c1320a2c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableStockSharesIssued_52c4e9e9-3178-49c7-8901-77ad491fce08" xlink:href="cart-20230930.xsd#cart_ExchangeableStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_cart_ExchangeableStockSharesIssued_52c4e9e9-3178-49c7-8901-77ad491fce08" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableStockSharesOutstanding_53bfbe98-0bf0-4407-8374-68c231c6d3be" xlink:href="cart-20230930.xsd#cart_ExchangeableStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_cart_ExchangeableStockSharesOutstanding_53bfbe98-0bf0-4407-8374-68c231c6d3be" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_120ab31e-f618-4690-8d03-bad2654ec706" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_bf85894b-9b87-445a-8ae9-b6a58cc170e1" xlink:to="loc_us-gaap_StatementTable_120ab31e-f618-4690-8d03-bad2654ec706" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_7bdb8d7c-5afa-4862-b4d8-5ddd61c1a2eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_120ab31e-f618-4690-8d03-bad2654ec706" xlink:to="loc_us-gaap_StatementClassOfStockAxis_7bdb8d7c-5afa-4862-b4d8-5ddd61c1a2eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7bdb8d7c-5afa-4862-b4d8-5ddd61c1a2eb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7bdb8d7c-5afa-4862-b4d8-5ddd61c1a2eb" xlink:to="loc_us-gaap_ClassOfStockDomain_7bdb8d7c-5afa-4862-b4d8-5ddd61c1a2eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_2ce2a091-9f67-4ae3-95d1-ec06bac6116e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7bdb8d7c-5afa-4862-b4d8-5ddd61c1a2eb" xlink:to="loc_us-gaap_ClassOfStockDomain_2ce2a091-9f67-4ae3-95d1-ec06bac6116e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_d09e1ba2-3b4c-4c3e-a0e0-dfcfb2cef4df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_2ce2a091-9f67-4ae3-95d1-ec06bac6116e" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_d09e1ba2-3b4c-4c3e-a0e0-dfcfb2cef4df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_f1df86d0-13b2-4caa-94c5-1406b51cca4e" xlink:href="cart-20230930.xsd#cart_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_2ce2a091-9f67-4ae3-95d1-ec06bac6116e" xlink:to="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_f1df86d0-13b2-4caa-94c5-1406b51cca4e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/CondensedConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersEquityDeficit" xlink:type="simple" xlink:href="cart-20230930.xsd#CondensedConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersEquityDeficit"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/CondensedConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersEquityDeficit" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_2e87e26d-7b97-43cc-a756-51fb53f20888" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_d1c7f0c2-8618-4ebe-a9e6-fcfd94e0c219" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInTemporaryEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2e87e26d-7b97-43cc-a756-51fb53f20888" xlink:to="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_d1c7f0c2-8618-4ebe-a9e6-fcfd94e0c219" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_53e10d69-4f96-41df-aa59-aef7bd73fb87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_d1c7f0c2-8618-4ebe-a9e6-fcfd94e0c219" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_53e10d69-4f96-41df-aa59-aef7bd73fb87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_31ddb607-94f7-44b5-a578-cbf4c4461c85" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_d1c7f0c2-8618-4ebe-a9e6-fcfd94e0c219" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_31ddb607-94f7-44b5-a578-cbf4c4461c85" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_TemporaryEquitySharesConversionOfConvertibleSecurities_957cf9e3-1a29-49b0-a427-c8023e7c3435" xlink:href="cart-20230930.xsd#cart_TemporaryEquitySharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_d1c7f0c2-8618-4ebe-a9e6-fcfd94e0c219" xlink:to="loc_cart_TemporaryEquitySharesConversionOfConvertibleSecurities_957cf9e3-1a29-49b0-a427-c8023e7c3435" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_TemporaryEquityValueConversionOfConvertibleSecurities_31dd6f78-08bd-4e9a-aff6-edc258dadc4f" xlink:href="cart-20230930.xsd#cart_TemporaryEquityValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_d1c7f0c2-8618-4ebe-a9e6-fcfd94e0c219" xlink:to="loc_cart_TemporaryEquityValueConversionOfConvertibleSecurities_31dd6f78-08bd-4e9a-aff6-edc258dadc4f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues_eb8909ce-f579-4ba3-8486-0e04b645122b" xlink:href="cart-20230930.xsd#cart_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_d1c7f0c2-8618-4ebe-a9e6-fcfd94e0c219" xlink:to="loc_cart_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues_eb8909ce-f579-4ba3-8486-0e04b645122b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues_ac5e2e49-c953-4d3c-aca0-bbbfaf8ca8a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_d1c7f0c2-8618-4ebe-a9e6-fcfd94e0c219" xlink:to="loc_us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues_ac5e2e49-c953-4d3c-aca0-bbbfaf8ca8a9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_bebdc91b-342b-4dff-925c-0f21050431e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_6b888d69-2eb5-4998-9d23-6fac985e8a72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2e87e26d-7b97-43cc-a756-51fb53f20888" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_a79bc09c-c22b-4c14-b380-970f735626ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_a79bc09c-c22b-4c14-b380-970f735626ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_dd19b0f9-a2f5-4e17-8918-e699fa2d8139" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockholdersEquity_dd19b0f9-a2f5-4e17-8918-e699fa2d8139" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableStockSharesOutstanding_e44ec107-65d8-4b91-bb70-cd5dae839b97" xlink:href="cart-20230930.xsd#cart_ExchangeableStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_cart_ExchangeableStockSharesOutstanding_e44ec107-65d8-4b91-bb70-cd5dae839b97" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_31467f39-2e5d-4ec9-898e-aecb23a43223" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_31467f39-2e5d-4ec9-898e-aecb23a43223" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_28c8e1ef-ddb5-45a0-b339-b465363545d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_28c8e1ef-ddb5-45a0-b339-b465363545d8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_StockIssuedDuringPeriodSharesWarrantsExercised_3cc7fdfe-d819-4d6a-a868-1199ca825330" xlink:href="cart-20230930.xsd#cart_StockIssuedDuringPeriodSharesWarrantsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_cart_StockIssuedDuringPeriodSharesWarrantsExercised_3cc7fdfe-d819-4d6a-a868-1199ca825330" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_StockIssuedDuringPeriodValueWarrantsExercised_2a2c235d-06d0-45e8-90c8-0ce236e59de4" xlink:href="cart-20230930.xsd#cart_StockIssuedDuringPeriodValueWarrantsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_cart_StockIssuedDuringPeriodValueWarrantsExercised_2a2c235d-06d0-45e8-90c8-0ce236e59de4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_7fd3a1ab-9476-4708-a30d-274c74749b0f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_7fd3a1ab-9476-4708-a30d-274c74749b0f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_6d2ddd2d-7750-4c69-90b3-e4c0f84927f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_6d2ddd2d-7750-4c69-90b3-e4c0f84927f7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_StockIssuedDuringPeriodSharesNonVotingCommonStockUponSettlementOfRestrictedStockUnits_a6ae4571-552c-4dd5-b7ed-00e5e81b8c48" xlink:href="cart-20230930.xsd#cart_StockIssuedDuringPeriodSharesNonVotingCommonStockUponSettlementOfRestrictedStockUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_cart_StockIssuedDuringPeriodSharesNonVotingCommonStockUponSettlementOfRestrictedStockUnits_a6ae4571-552c-4dd5-b7ed-00e5e81b8c48" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_1ca26904-33a6-4e3b-a04a-8a7d75e82b75" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_1ca26904-33a6-4e3b-a04a-8a7d75e82b75" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_81287e35-cd1d-4c69-9a20-e989fadf2a71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_81287e35-cd1d-4c69-9a20-e989fadf2a71" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_8e4feb5b-12f9-4f78-996c-f4fccb702c21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_8e4feb5b-12f9-4f78-996c-f4fccb702c21" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_StockIssuedDuringPeriodSharesConversionOfExchangeableShares_3b0ec4ac-32ea-4747-b58f-da52d8b94f18" xlink:href="cart-20230930.xsd#cart_StockIssuedDuringPeriodSharesConversionOfExchangeableShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_cart_StockIssuedDuringPeriodSharesConversionOfExchangeableShares_3b0ec4ac-32ea-4747-b58f-da52d8b94f18" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationForfeited_5de0b632-a7d4-4acf-ba50-6ef74f1fe7c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationForfeited"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationForfeited_5de0b632-a7d4-4acf-ba50-6ef74f1fe7c1" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_0f585388-56ec-494c-9bf1-e2ccf35086da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_0f585388-56ec-494c-9bf1-e2ccf35086da" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_StockIssuedDuringPeriodSharesCommonStockUponExerciseOfWarrants_52012ff1-b9b1-4152-b8e2-908d96b6d615" xlink:href="cart-20230930.xsd#cart_StockIssuedDuringPeriodSharesCommonStockUponExerciseOfWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_cart_StockIssuedDuringPeriodSharesCommonStockUponExerciseOfWarrants_52012ff1-b9b1-4152-b8e2-908d96b6d615" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_e3b5a2bb-b1ec-4b8e-9292-4fcd0e6f234b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_bb154186-04dc-4402-a657-c84af996baa6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_bb154186-04dc-4402-a657-c84af996baa6" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_a3d5636e-533e-4e0d-9dab-ae8cbec42c3b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_a3d5636e-533e-4e0d-9dab-ae8cbec42c3b" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_3b81c019-02eb-4768-b362-4d45a2cd615b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_3b81c019-02eb-4768-b362-4d45a2cd615b" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_bed17951-31af-454a-8385-6645cf6365e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_bed17951-31af-454a-8385-6645cf6365e2" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_4b1d5e01-ff53-4e99-911a-055827f7c899" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_4b1d5e01-ff53-4e99-911a-055827f7c899" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_dfc9f58f-408c-4f21-9a39-16545db07fd8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_81d256b6-1cc6-48a8-8336-82e117808fc3" xlink:to="loc_us-gaap_NetIncomeLoss_dfc9f58f-408c-4f21-9a39-16545db07fd8" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_8bafd97c-b74e-458d-b400-5d7452c4891b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableStockSharesOutstanding_7f063b64-937d-40ba-b263-f3fdf15086d2" xlink:href="cart-20230930.xsd#cart_ExchangeableStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_5122dab9-4a73-410a-94b9-47efa9ed750f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_e75566fc-f767-42db-a573-b4c12e96f0e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_2e87e26d-7b97-43cc-a756-51fb53f20888" xlink:to="loc_us-gaap_StatementTable_e75566fc-f767-42db-a573-b4c12e96f0e8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_8b0da3fd-bf34-40d1-816a-4d4e7d135217" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e75566fc-f767-42db-a573-b4c12e96f0e8" xlink:to="loc_us-gaap_StatementClassOfStockAxis_8b0da3fd-bf34-40d1-816a-4d4e7d135217" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_8b0da3fd-bf34-40d1-816a-4d4e7d135217_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8b0da3fd-bf34-40d1-816a-4d4e7d135217" xlink:to="loc_us-gaap_ClassOfStockDomain_8b0da3fd-bf34-40d1-816a-4d4e7d135217_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_78d4d522-a5ed-4ac0-9ea8-846518fc05e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8b0da3fd-bf34-40d1-816a-4d4e7d135217" xlink:to="loc_us-gaap_ClassOfStockDomain_78d4d522-a5ed-4ac0-9ea8-846518fc05e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_38ba56ad-39da-484e-98e9-4189f3879c28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_78d4d522-a5ed-4ac0-9ea8-846518fc05e4" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_38ba56ad-39da-484e-98e9-4189f3879c28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_8fb560ab-b2f9-4194-9f4e-5eb948527135" xlink:href="cart-20230930.xsd#cart_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_78d4d522-a5ed-4ac0-9ea8-846518fc05e4" xlink:to="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_8fb560ab-b2f9-4194-9f4e-5eb948527135" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_586549cc-ae71-4276-a59e-d5f21bd4526a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e75566fc-f767-42db-a573-b4c12e96f0e8" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_586549cc-ae71-4276-a59e-d5f21bd4526a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_586549cc-ae71-4276-a59e-d5f21bd4526a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_586549cc-ae71-4276-a59e-d5f21bd4526a" xlink:to="loc_us-gaap_EquityComponentDomain_586549cc-ae71-4276-a59e-d5f21bd4526a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_93c8a1d8-efbb-4cd4-aea5-9c0d237b0734" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_586549cc-ae71-4276-a59e-d5f21bd4526a" xlink:to="loc_us-gaap_EquityComponentDomain_93c8a1d8-efbb-4cd4-aea5-9c0d237b0734" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_20aa8984-cb3b-49b1-bc1d-8b5e61979c0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_93c8a1d8-efbb-4cd4-aea5-9c0d237b0734" xlink:to="loc_us-gaap_CommonStockMember_20aa8984-cb3b-49b1-bc1d-8b5e61979c0b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableSharesMember_209f7053-0da3-4c05-b154-f23979e37097" xlink:href="cart-20230930.xsd#cart_ExchangeableSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_93c8a1d8-efbb-4cd4-aea5-9c0d237b0734" xlink:to="loc_cart_ExchangeableSharesMember_209f7053-0da3-4c05-b154-f23979e37097" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_617f0b33-0a4a-4dfb-99ec-ae18870e94a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_93c8a1d8-efbb-4cd4-aea5-9c0d237b0734" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_617f0b33-0a4a-4dfb-99ec-ae18870e94a0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_2c3ac1f0-ea80-43fb-bb11-0bfc1eef7ab7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_93c8a1d8-efbb-4cd4-aea5-9c0d237b0734" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_2c3ac1f0-ea80-43fb-bb11-0bfc1eef7ab7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_d57e7c4d-b716-42b8-8d78-57f655c5c539" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_93c8a1d8-efbb-4cd4-aea5-9c0d237b0734" xlink:to="loc_us-gaap_RetainedEarningsMember_d57e7c4d-b716-42b8-8d78-57f655c5c539" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/BusinessDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#BusinessDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/BusinessDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_1f10f954-5516-4ada-8eb8-b50bccfe34fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_1f10f954-5516-4ada-8eb8-b50bccfe34fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_e5e11de7-7dee-4381-bc6c-54aa891b866c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_e5e11de7-7dee-4381-bc6c-54aa891b866c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_52b9e043-9463-4bb3-b645-b1f72a0a0fc8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_52b9e043-9463-4bb3-b645-b1f72a0a0fc8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_StockExchangedDuringPeriodShares_f31aefdf-fa98-423c-99a6-f660803acbfe" xlink:href="cart-20230930.xsd#cart_StockExchangedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_cart_StockExchangedDuringPeriodShares_f31aefdf-fa98-423c-99a6-f660803acbfe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_5cbf4e29-12a5-436b-9624-98cc40cbe160" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_5cbf4e29-12a5-436b-9624-98cc40cbe160" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SharesAuthorized_c42ecbc1-b016-4b7b-9701-87672e6c38cc" xlink:href="cart-20230930.xsd#cart_SharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_cart_SharesAuthorized_c42ecbc1-b016-4b7b-9701-87672e6c38cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_64d82ddc-57d3-4c70-a689-e6b6be30decc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_64d82ddc-57d3-4c70-a689-e6b6be30decc" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_8d62de15-89a8-40bd-8f91-d7b4b04e52e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_8d62de15-89a8-40bd-8f91-d7b4b04e52e3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_1d67323d-a34e-4868-92e4-72f75ddbe161" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_411f4e02-eb92-401e-8637-ba452f8d3f36" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_1d67323d-a34e-4868-92e4-72f75ddbe161" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_82fd9981-12ce-488b-b12c-7922eb2292b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1d67323d-a34e-4868-92e4-72f75ddbe161" xlink:to="loc_us-gaap_StatementClassOfStockAxis_82fd9981-12ce-488b-b12c-7922eb2292b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_82fd9981-12ce-488b-b12c-7922eb2292b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_82fd9981-12ce-488b-b12c-7922eb2292b8" xlink:to="loc_us-gaap_ClassOfStockDomain_82fd9981-12ce-488b-b12c-7922eb2292b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_252c2271-b9a8-43df-95cb-fa91447eef74" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_82fd9981-12ce-488b-b12c-7922eb2292b8" xlink:to="loc_us-gaap_ClassOfStockDomain_252c2271-b9a8-43df-95cb-fa91447eef74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_e97e5465-9c98-4ba2-b5ab-5e362d803238" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_252c2271-b9a8-43df-95cb-fa91447eef74" xlink:to="loc_us-gaap_CommonStockMember_e97e5465-9c98-4ba2-b5ab-5e362d803238" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_acf09652-55e6-4452-8b74-8dbcc8687d4a" xlink:href="cart-20230930.xsd#cart_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_252c2271-b9a8-43df-95cb-fa91447eef74" xlink:to="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_acf09652-55e6-4452-8b74-8dbcc8687d4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_NonVotingCommonStockMember_6ff5aab2-a06f-42e1-a323-d8eae3f25aff" xlink:href="cart-20230930.xsd#cart_NonVotingCommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_252c2271-b9a8-43df-95cb-fa91447eef74" xlink:to="loc_cart_NonVotingCommonStockMember_6ff5aab2-a06f-42e1-a323-d8eae3f25aff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_9ca4ca53-5e4a-42bf-8462-28c197bd298b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1d67323d-a34e-4868-92e4-72f75ddbe161" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_9ca4ca53-5e4a-42bf-8462-28c197bd298b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_9ca4ca53-5e4a-42bf-8462-28c197bd298b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_9ca4ca53-5e4a-42bf-8462-28c197bd298b" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_9ca4ca53-5e4a-42bf-8462-28c197bd298b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_71178613-da48-433f-ae2d-5fea652199fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_9ca4ca53-5e4a-42bf-8462-28c197bd298b" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_71178613-da48-433f-ae2d-5fea652199fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_e879ebd7-a5e4-4e36-800b-73f17ca44c94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IPOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_71178613-da48-433f-ae2d-5fea652199fd" xlink:to="loc_us-gaap_IPOMember_e879ebd7-a5e4-4e36-800b-73f17ca44c94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrivatePlacementMember_f31144e8-07e5-4040-851e-268a9f7e7a2a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrivatePlacementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_71178613-da48-433f-ae2d-5fea652199fd" xlink:to="loc_us-gaap_PrivatePlacementMember_f31144e8-07e5-4040-851e-268a9f7e7a2a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/SignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#SignificantAccountingPoliciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/SignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_f0809792-0a9b-43f4-8399-49774c7fb8db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_bdf0a73e-8f1f-4b85-9d99-b06655a5a601" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0809792-0a9b-43f4-8399-49774c7fb8db" xlink:to="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_bdf0a73e-8f1f-4b85-9d99-b06655a5a601" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_7e3d5fd9-9064-41c5-acc9-89b3eff42591" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f0809792-0a9b-43f4-8399-49774c7fb8db" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_7e3d5fd9-9064-41c5-acc9-89b3eff42591" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_9526a0a4-f27a-4ecf-b550-097c5428393d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_7e3d5fd9-9064-41c5-acc9-89b3eff42591" xlink:to="loc_us-gaap_StatementClassOfStockAxis_9526a0a4-f27a-4ecf-b550-097c5428393d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_9526a0a4-f27a-4ecf-b550-097c5428393d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9526a0a4-f27a-4ecf-b550-097c5428393d" xlink:to="loc_us-gaap_ClassOfStockDomain_9526a0a4-f27a-4ecf-b550-097c5428393d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_1c8d59f0-8e9c-4465-8fbe-f14acf362644" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9526a0a4-f27a-4ecf-b550-097c5428393d" xlink:to="loc_us-gaap_ClassOfStockDomain_1c8d59f0-8e9c-4465-8fbe-f14acf362644" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_fbac5f51-be47-4589-a70d-18af390c1608" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1c8d59f0-8e9c-4465-8fbe-f14acf362644" xlink:to="loc_us-gaap_CommonStockMember_fbac5f51-be47-4589-a70d-18af390c1608" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/RevenueReconciliationofRevenuefromSegmentstoConsolidatedDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#RevenueReconciliationofRevenuefromSegmentstoConsolidatedDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/RevenueReconciliationofRevenuefromSegmentstoConsolidatedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_fa15e943-a906-4cc5-8b00-93bc8034ca0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_3c50a6e1-5456-4f98-9a28-d428aa7ee038" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_fa15e943-a906-4cc5-8b00-93bc8034ca0b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_3c50a6e1-5456-4f98-9a28-d428aa7ee038" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_1790fb3b-d428-4a68-bcdf-d63329107a4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_fa15e943-a906-4cc5-8b00-93bc8034ca0b" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_1790fb3b-d428-4a68-bcdf-d63329107a4e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_72d8a67b-e6c6-4215-84e8-14ee09dccaac" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_1790fb3b-d428-4a68-bcdf-d63329107a4e" xlink:to="loc_srt_ProductOrServiceAxis_72d8a67b-e6c6-4215-84e8-14ee09dccaac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_72d8a67b-e6c6-4215-84e8-14ee09dccaac_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_72d8a67b-e6c6-4215-84e8-14ee09dccaac" xlink:to="loc_srt_ProductsAndServicesDomain_72d8a67b-e6c6-4215-84e8-14ee09dccaac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_d75cb7ec-e5da-401d-adb4-414bd786250f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_72d8a67b-e6c6-4215-84e8-14ee09dccaac" xlink:to="loc_srt_ProductsAndServicesDomain_d75cb7ec-e5da-401d-adb4-414bd786250f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_TransactionMember_6dd75316-6d9d-4f5a-bdaf-e6afef0edb5c" xlink:href="cart-20230930.xsd#cart_TransactionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d75cb7ec-e5da-401d-adb4-414bd786250f" xlink:to="loc_cart_TransactionMember_6dd75316-6d9d-4f5a-bdaf-e6afef0edb5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_AdvertisingAndOtherMember_ad0e6436-b7b2-4f44-bfae-dd17a1947c84" xlink:href="cart-20230930.xsd#cart_AdvertisingAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d75cb7ec-e5da-401d-adb4-414bd786250f" xlink:to="loc_cart_AdvertisingAndOtherMember_ad0e6436-b7b2-4f44-bfae-dd17a1947c84" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/RevenueRevenuefromExternalCustomersbyGeographicAreasDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#RevenueRevenuefromExternalCustomersbyGeographicAreasDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/RevenueRevenuefromExternalCustomersbyGeographicAreasDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_53d2c7fd-b275-4cec-a53e-5e768b8e8c6b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_ebd8dcee-4c3b-4f86-a7b2-b1342ebcbac4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_53d2c7fd-b275-4cec-a53e-5e768b8e8c6b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_ebd8dcee-4c3b-4f86-a7b2-b1342ebcbac4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_e2c532cb-cdcd-442d-a79e-2213f9d96ca0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_53d2c7fd-b275-4cec-a53e-5e768b8e8c6b" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_e2c532cb-cdcd-442d-a79e-2213f9d96ca0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_b472c018-75b7-4cd4-8a4d-618f08b23faa" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e2c532cb-cdcd-442d-a79e-2213f9d96ca0" xlink:to="loc_srt_StatementGeographicalAxis_b472c018-75b7-4cd4-8a4d-618f08b23faa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_b472c018-75b7-4cd4-8a4d-618f08b23faa_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_b472c018-75b7-4cd4-8a4d-618f08b23faa" xlink:to="loc_srt_SegmentGeographicalDomain_b472c018-75b7-4cd4-8a4d-618f08b23faa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_c997cc33-052c-49f5-811b-d18ac9f9444d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_b472c018-75b7-4cd4-8a4d-618f08b23faa" xlink:to="loc_srt_SegmentGeographicalDomain_c997cc33-052c-49f5-811b-d18ac9f9444d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_5c6b49f4-9d14-4a3f-aac8-675ced718a3b" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_c997cc33-052c-49f5-811b-d18ac9f9444d" xlink:to="loc_country_US_5c6b49f4-9d14-4a3f-aac8-675ced718a3b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_92bc5431-a7a2-4340-8e57-d7f7b618777f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_c997cc33-052c-49f5-811b-d18ac9f9444d" xlink:to="loc_us-gaap_NonUsMember_92bc5431-a7a2-4340-8e57-d7f7b618777f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/RevenueNarrativeDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#RevenueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/RevenueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_125ca053-d12e-4369-a1d9-6b2b1f8d5ed1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_125ca053-d12e-4369-a1d9-6b2b1f8d5ed1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_7704bbc0-3926-4a2a-9c78-2382241466cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_7704bbc0-3926-4a2a-9c78-2382241466cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_8666c157-d2b4-4a37-87a4-2592f5e210ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_8666c157-d2b4-4a37-87a4-2592f5e210ec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightNumberOfTimeOrPerformanceBasedMilestonesAchievement_2a3f79cb-7b6e-4ec9-a452-58ca906ce6a6" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightNumberOfTimeOrPerformanceBasedMilestonesAchievement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightNumberOfTimeOrPerformanceBasedMilestonesAchievement_2a3f79cb-7b6e-4ec9-a452-58ca906ce6a6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightVested_88b9bb58-b4d0-4a22-82de-58eb0b83cade" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightVested_88b9bb58-b4d0-4a22-82de-58eb0b83cade" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightElapsedDuration_70e44675-accc-4a0f-9249-1b95181aa164" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightElapsedDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightElapsedDuration_70e44675-accc-4a0f-9249-1b95181aa164" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightAnniversaryTerm_d63095f3-76e3-4650-ab28-a5d252f8f16d" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightAnniversaryTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightAnniversaryTerm_d63095f3-76e3-4650-ab28-a5d252f8f16d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_d5ef74a1-95d8-4a3e-9086-2394511ef719" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_d5ef74a1-95d8-4a3e-9086-2394511ef719" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightExercisable_139c18c7-7c6c-48f1-987a-8d268867d6e3" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightExercisable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightExercisable_139c18c7-7c6c-48f1-987a-8d268867d6e3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightWarrantsOutstandingWeightedAverageRemainingContractualTerm_aeb9af7a-789f-43f6-acd0-60a50ca843d2" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightWarrantsOutstandingWeightedAverageRemainingContractualTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightWarrantsOutstandingWeightedAverageRemainingContractualTerm_aeb9af7a-789f-43f6-acd0-60a50ca843d2" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightWarrantsVestedWeightedAverageRemainingContractualTerm_21070f30-2072-42f3-8c28-cbeae6753215" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightWarrantsVestedWeightedAverageRemainingContractualTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightWarrantsVestedWeightedAverageRemainingContractualTerm_21070f30-2072-42f3-8c28-cbeae6753215" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightWarrantsVestedIntrinsicValue_e74063ea-fb90-412b-b87b-4d3e3cad580c" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightWarrantsVestedIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightWarrantsVestedIntrinsicValue_e74063ea-fb90-412b-b87b-4d3e3cad580c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightWarrantsOutstandingIntrinsicValue_41110680-af74-4abb-b9c2-42b50958d1bc" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightWarrantsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightWarrantsOutstandingIntrinsicValue_41110680-af74-4abb-b9c2-42b50958d1bc" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightExercisedCancelledOrExpired_f26554f7-8c0c-4a71-adb5-a46fc94c4c3b" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightExercisedCancelledOrExpired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightExercisedCancelledOrExpired_f26554f7-8c0c-4a71-adb5-a46fc94c4c3b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssued_b6d80434-63da-4011-811b-afe08bca2062" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_SharesIssued_b6d80434-63da-4011-811b-afe08bca2062" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightAnniversaryTerm1_ac7ea81d-76bb-4c48-b69c-90a44a2d91d6" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightAnniversaryTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightAnniversaryTerm1_ac7ea81d-76bb-4c48-b69c-90a44a2d91d6" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightAnniversaryTerm2_9340668b-0e56-4cb2-8db8-8f69c92ca3e7" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightAnniversaryTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightAnniversaryTerm2_9340668b-0e56-4cb2-8db8-8f69c92ca3e7" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightExercisableNumberOfTranches_02d18578-85b8-4337-973b-d456f0430b4d" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightExercisableNumberOfTranches"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightExercisableNumberOfTranches_02d18578-85b8-4337-973b-d456f0430b4d" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightVestingDurationThereafter_48c6ebb3-8627-44e0-9179-c92a0c16c0f2" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightVestingDurationThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightVestingDurationThereafter_48c6ebb3-8627-44e0-9179-c92a0c16c0f2" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightExpirationDuration_ea6d9e40-38c6-48e8-b073-9f4304c03e1d" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightExpirationDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightExpirationDuration_ea6d9e40-38c6-48e8-b073-9f4304c03e1d" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightAnniversaryTerm3_c671f590-af9d-49f4-98a8-aa9581b1ef0b" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightAnniversaryTerm3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightAnniversaryTerm3_c671f590-af9d-49f4-98a8-aa9581b1ef0b" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ClassOfWarrantOrRightExercised_91002b17-268f-4d72-9f1b-d621175b9ae3" xlink:href="cart-20230930.xsd#cart_ClassOfWarrantOrRightExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_ClassOfWarrantOrRightExercised_91002b17-268f-4d72-9f1b-d621175b9ae3" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromWarrantExercises_352082a2-b99d-4097-8ff7-07b220bb6f5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromWarrantExercises"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_ProceedsFromWarrantExercises_352082a2-b99d-4097-8ff7-07b220bb6f5d" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_41ca3830-87cd-41e7-840e-c63375d100f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_41ca3830-87cd-41e7-840e-c63375d100f9" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_66ea9416-37ef-4e9a-b1fe-cd75167a724c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_66ea9416-37ef-4e9a-b1fe-cd75167a724c" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockNumberOfTimeBasedMilestonesAchievement_7a62635e-7965-40a0-8d52-32531f47947a" xlink:href="cart-20230930.xsd#cart_SaleOfStockNumberOfTimeBasedMilestonesAchievement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_SaleOfStockNumberOfTimeBasedMilestonesAchievement_7a62635e-7965-40a0-8d52-32531f47947a" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockVested_43058adb-74a8-43e9-a542-c64530ca75e7" xlink:href="cart-20230930.xsd#cart_SaleOfStockVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_SaleOfStockVested_43058adb-74a8-43e9-a542-c64530ca75e7" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockAnniversaryTerm1_1919068e-9eb5-4d90-8080-a492c6444e6a" xlink:href="cart-20230930.xsd#cart_SaleOfStockAnniversaryTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_SaleOfStockAnniversaryTerm1_1919068e-9eb5-4d90-8080-a492c6444e6a" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockAnniversaryTerm2_4d967200-ae4a-482b-81ef-8a1916e529b3" xlink:href="cart-20230930.xsd#cart_SaleOfStockAnniversaryTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_SaleOfStockAnniversaryTerm2_4d967200-ae4a-482b-81ef-8a1916e529b3" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockAnniversaryTerm3_e729d336-9f8c-47c6-879c-935b1557b052" xlink:href="cart-20230930.xsd#cart_SaleOfStockAnniversaryTerm3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_SaleOfStockAnniversaryTerm3_e729d336-9f8c-47c6-879c-935b1557b052" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockAnniversaryTerm4_477de0d6-992f-4be3-b8c1-b9ec64682bf5" xlink:href="cart-20230930.xsd#cart_SaleOfStockAnniversaryTerm4"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_SaleOfStockAnniversaryTerm4_477de0d6-992f-4be3-b8c1-b9ec64682bf5" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockOutstanding_8386b00f-20e6-454f-93c6-46440b1fbaa8" xlink:href="cart-20230930.xsd#cart_SaleOfStockOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_cart_SaleOfStockOutstanding_8386b00f-20e6-454f-93c6-46440b1fbaa8" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_44f806a2-74bf-46e7-a306-3ea87e6e49cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01136513-6b8a-4813-aba1-05dac5aa38a0" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_44f806a2-74bf-46e7-a306-3ea87e6e49cd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_d5cbd14a-94e9-4873-ac24-cd42cf090ad8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_44f806a2-74bf-46e7-a306-3ea87e6e49cd" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_d5cbd14a-94e9-4873-ac24-cd42cf090ad8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_d5cbd14a-94e9-4873-ac24-cd42cf090ad8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_d5cbd14a-94e9-4873-ac24-cd42cf090ad8" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_d5cbd14a-94e9-4873-ac24-cd42cf090ad8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_e2d52535-9075-4a2a-978c-fc159b878d98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_d5cbd14a-94e9-4873-ac24-cd42cf090ad8" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_e2d52535-9075-4a2a-978c-fc159b878d98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_November2017RetailerWarrantsMember_358ac9a3-0c69-4ac6-8db9-3713420004ba" xlink:href="cart-20230930.xsd#cart_November2017RetailerWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_e2d52535-9075-4a2a-978c-fc159b878d98" xlink:to="loc_cart_November2017RetailerWarrantsMember_358ac9a3-0c69-4ac6-8db9-3713420004ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_November2017RetailerWarrantsTimeBasedMilestoneMember_f9c10123-43e6-466b-8dfd-5e6d856eadb2" xlink:href="cart-20230930.xsd#cart_November2017RetailerWarrantsTimeBasedMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_November2017RetailerWarrantsMember_358ac9a3-0c69-4ac6-8db9-3713420004ba" xlink:to="loc_cart_November2017RetailerWarrantsTimeBasedMilestoneMember_f9c10123-43e6-466b-8dfd-5e6d856eadb2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_November2017RetailerWarrantsPerformanceBasedMilestoneMember_e3c736ba-ead3-43b5-96e5-bc73d768cb2c" xlink:href="cart-20230930.xsd#cart_November2017RetailerWarrantsPerformanceBasedMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_November2017RetailerWarrantsMember_358ac9a3-0c69-4ac6-8db9-3713420004ba" xlink:to="loc_cart_November2017RetailerWarrantsPerformanceBasedMilestoneMember_e3c736ba-ead3-43b5-96e5-bc73d768cb2c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_July2018RetailerWarrantsMember_56f5c4b4-66f3-4c1e-a62f-15a1da308e31" xlink:href="cart-20230930.xsd#cart_July2018RetailerWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_e2d52535-9075-4a2a-978c-fc159b878d98" xlink:to="loc_cart_July2018RetailerWarrantsMember_56f5c4b4-66f3-4c1e-a62f-15a1da308e31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_8a0d2272-1535-447e-82ff-131ba573a028" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_44f806a2-74bf-46e7-a306-3ea87e6e49cd" xlink:to="loc_us-gaap_StatementClassOfStockAxis_8a0d2272-1535-447e-82ff-131ba573a028" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_8a0d2272-1535-447e-82ff-131ba573a028_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8a0d2272-1535-447e-82ff-131ba573a028" xlink:to="loc_us-gaap_ClassOfStockDomain_8a0d2272-1535-447e-82ff-131ba573a028_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_9a5e1d5d-15aa-4b45-98e4-07e4ee2db00b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8a0d2272-1535-447e-82ff-131ba573a028" xlink:to="loc_us-gaap_ClassOfStockDomain_9a5e1d5d-15aa-4b45-98e4-07e4ee2db00b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_NonVotingCommonStockMember_366a9f55-9db3-458e-ba9c-2fd62b803dd5" xlink:href="cart-20230930.xsd#cart_NonVotingCommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_9a5e1d5d-15aa-4b45-98e4-07e4ee2db00b" xlink:to="loc_cart_NonVotingCommonStockMember_366a9f55-9db3-458e-ba9c-2fd62b803dd5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_ddf23977-b1a7-43cd-962d-95648b35b78a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_44f806a2-74bf-46e7-a306-3ea87e6e49cd" xlink:to="loc_us-gaap_VestingAxis_ddf23977-b1a7-43cd-962d-95648b35b78a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_ddf23977-b1a7-43cd-962d-95648b35b78a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_ddf23977-b1a7-43cd-962d-95648b35b78a" xlink:to="loc_us-gaap_VestingDomain_ddf23977-b1a7-43cd-962d-95648b35b78a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_58eb315c-f4ab-4277-b306-b406e83782a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_ddf23977-b1a7-43cd-962d-95648b35b78a" xlink:to="loc_us-gaap_VestingDomain_58eb315c-f4ab-4277-b306-b406e83782a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_A12And24MonthAnniversaryMember_4ae11ed1-f09a-401e-ad6f-86cf5e3f297c" xlink:href="cart-20230930.xsd#cart_A12And24MonthAnniversaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_58eb315c-f4ab-4277-b306-b406e83782a3" xlink:to="loc_cart_A12And24MonthAnniversaryMember_4ae11ed1-f09a-401e-ad6f-86cf5e3f297c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_EverySixMonthsThereafterMember_ebead405-b4f6-432e-9c26-fab76ac7fc83" xlink:href="cart-20230930.xsd#cart_EverySixMonthsThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_58eb315c-f4ab-4277-b306-b406e83782a3" xlink:to="loc_cart_EverySixMonthsThereafterMember_ebead405-b4f6-432e-9c26-fab76ac7fc83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_A36And48MonthAnniversaryMember_b00d776e-6ac9-41f2-8582-7a109899c127" xlink:href="cart-20230930.xsd#cart_A36And48MonthAnniversaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_58eb315c-f4ab-4277-b306-b406e83782a3" xlink:to="loc_cart_A36And48MonthAnniversaryMember_b00d776e-6ac9-41f2-8582-7a109899c127" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_788969f8-3b31-4734-b557-2eadbfc93fc9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_44f806a2-74bf-46e7-a306-3ea87e6e49cd" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_788969f8-3b31-4734-b557-2eadbfc93fc9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_788969f8-3b31-4734-b557-2eadbfc93fc9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_788969f8-3b31-4734-b557-2eadbfc93fc9" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_788969f8-3b31-4734-b557-2eadbfc93fc9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_afc3e128-2a5f-45d3-b4fa-a46f86612e96" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_788969f8-3b31-4734-b557-2eadbfc93fc9" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_afc3e128-2a5f-45d3-b4fa-a46f86612e96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SubscriptionAgreementMember_c6262849-a3be-4eed-b490-a56664b67709" xlink:href="cart-20230930.xsd#cart_SubscriptionAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_afc3e128-2a5f-45d3-b4fa-a46f86612e96" xlink:to="loc_cart_SubscriptionAgreementMember_c6262849-a3be-4eed-b490-a56664b67709" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/FairValueMeasurementsSummaryofAssetsandLiabilitiesMeasuredatFairValueDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#FairValueMeasurementsSummaryofAssetsandLiabilitiesMeasuredatFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/FairValueMeasurementsSummaryofAssetsandLiabilitiesMeasuredatFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_37e99ebb-f25a-4e60-ae1f-30cdb7d07f07" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_5bde0449-eabf-419a-a6b1-b0a988f173d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_37e99ebb-f25a-4e60-ae1f-30cdb7d07f07" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_5bde0449-eabf-419a-a6b1-b0a988f173d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_39dc06e5-f56f-4381-ae1f-53ddd019b0c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_37e99ebb-f25a-4e60-ae1f-30cdb7d07f07" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_39dc06e5-f56f-4381-ae1f-53ddd019b0c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f6eb9fe7-2f2a-4888-b559-abe05f3ae3fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_37e99ebb-f25a-4e60-ae1f-30cdb7d07f07" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f6eb9fe7-2f2a-4888-b559-abe05f3ae3fd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c98e3d9c-0381-431b-a4f4-579f0821046f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f6eb9fe7-2f2a-4888-b559-abe05f3ae3fd" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c98e3d9c-0381-431b-a4f4-579f0821046f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c98e3d9c-0381-431b-a4f4-579f0821046f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c98e3d9c-0381-431b-a4f4-579f0821046f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c98e3d9c-0381-431b-a4f4-579f0821046f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6e57e13b-df34-417d-ad86-b84505bebd7b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c98e3d9c-0381-431b-a4f4-579f0821046f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6e57e13b-df34-417d-ad86-b84505bebd7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_cfabc21d-f378-4f36-9162-5dd26438988d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6e57e13b-df34-417d-ad86-b84505bebd7b" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_cfabc21d-f378-4f36-9162-5dd26438988d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_f1823da0-2123-4546-9c28-f972c2bdf730" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6e57e13b-df34-417d-ad86-b84505bebd7b" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_f1823da0-2123-4546-9c28-f972c2bdf730" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_58caf175-6f5c-4f2a-95c8-6c80ed0d8a38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6e57e13b-df34-417d-ad86-b84505bebd7b" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_58caf175-6f5c-4f2a-95c8-6c80ed0d8a38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_33e6e0b5-a549-437a-a74a-a739d4ef04e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f6eb9fe7-2f2a-4888-b559-abe05f3ae3fd" xlink:to="loc_us-gaap_FinancialInstrumentAxis_33e6e0b5-a549-437a-a74a-a739d4ef04e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_33e6e0b5-a549-437a-a74a-a739d4ef04e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_33e6e0b5-a549-437a-a74a-a739d4ef04e4" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_33e6e0b5-a549-437a-a74a-a739d4ef04e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3cf6b79b-d628-4230-a49d-36a05798552f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_33e6e0b5-a549-437a-a74a-a739d4ef04e4" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3cf6b79b-d628-4230-a49d-36a05798552f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_5b97a483-67e9-4344-bb6a-735333c97910" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3cf6b79b-d628-4230-a49d-36a05798552f" xlink:to="loc_us-gaap_MoneyMarketFundsMember_5b97a483-67e9-4344-bb6a-735333c97910" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_9c3b3fa8-86d4-4962-a38f-8d33eb4ba589" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3cf6b79b-d628-4230-a49d-36a05798552f" xlink:to="loc_us-gaap_CommercialPaperMember_9c3b3fa8-86d4-4962-a38f-8d33eb4ba589" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_9b8e1f25-5296-4247-8db8-de37e31ac905" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3cf6b79b-d628-4230-a49d-36a05798552f" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_9b8e1f25-5296-4247-8db8-de37e31ac905" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_9d9cab48-1f66-49d3-880e-a00925261342" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3cf6b79b-d628-4230-a49d-36a05798552f" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_9d9cab48-1f66-49d3-880e-a00925261342" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_e6535f11-e87e-43aa-b363-d75847fa937e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f6eb9fe7-2f2a-4888-b559-abe05f3ae3fd" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_e6535f11-e87e-43aa-b363-d75847fa937e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_e6535f11-e87e-43aa-b363-d75847fa937e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_e6535f11-e87e-43aa-b363-d75847fa937e" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_e6535f11-e87e-43aa-b363-d75847fa937e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_21d9dc9b-2c99-457d-ab05-e255670b7c73" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_e6535f11-e87e-43aa-b363-d75847fa937e" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_21d9dc9b-2c99-457d-ab05-e255670b7c73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_5e122f40-ebb6-4c59-bfa6-b08fe6dc7354" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_21d9dc9b-2c99-457d-ab05-e255670b7c73" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_5e122f40-ebb6-4c59-bfa6-b08fe6dc7354" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_06f3550d-33cf-483e-824b-1eb22fbd248b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f6eb9fe7-2f2a-4888-b559-abe05f3ae3fd" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_06f3550d-33cf-483e-824b-1eb22fbd248b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_06f3550d-33cf-483e-824b-1eb22fbd248b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_06f3550d-33cf-483e-824b-1eb22fbd248b" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_06f3550d-33cf-483e-824b-1eb22fbd248b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_647bd102-a90d-497e-ba1a-256a3b14d29d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_06f3550d-33cf-483e-824b-1eb22fbd248b" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_647bd102-a90d-497e-ba1a-256a3b14d29d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsMember_5972faf8-02bf-4c17-87af-d55d50331b32" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_647bd102-a90d-497e-ba1a-256a3b14d29d" xlink:to="loc_us-gaap_CashEquivalentsMember_5972faf8-02bf-4c17-87af-d55d50331b32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShortTermMarketableSecuritiesMember_f50397d5-ba0f-4b6f-833d-6c3ca0754554" xlink:href="cart-20230930.xsd#cart_ShortTermMarketableSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_647bd102-a90d-497e-ba1a-256a3b14d29d" xlink:to="loc_cart_ShortTermMarketableSecuritiesMember_f50397d5-ba0f-4b6f-833d-6c3ca0754554" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_LongTermMarketableSecuritiesMember_0d39ca75-30d7-4feb-a50e-482a2e4ed863" xlink:href="cart-20230930.xsd#cart_LongTermMarketableSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_647bd102-a90d-497e-ba1a-256a3b14d29d" xlink:to="loc_cart_LongTermMarketableSecuritiesMember_0d39ca75-30d7-4feb-a50e-482a2e4ed863" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/InvestmentsAmortizedCostVersusFairValueDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#InvestmentsAmortizedCostVersusFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/InvestmentsAmortizedCostVersusFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_1a0f4ac3-251a-4f38-927d-f5a4129e3bb8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_f858b78d-67ab-4dfb-8deb-c48d13e860b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_1a0f4ac3-251a-4f38-927d-f5a4129e3bb8" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_f858b78d-67ab-4dfb-8deb-c48d13e860b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_95bbd7a9-6587-4423-a321-031698d4fb83" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_1a0f4ac3-251a-4f38-927d-f5a4129e3bb8" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_95bbd7a9-6587-4423-a321-031698d4fb83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_a073fd2a-9c69-43d4-8b6d-4e52aa6a47f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_1a0f4ac3-251a-4f38-927d-f5a4129e3bb8" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_a073fd2a-9c69-43d4-8b6d-4e52aa6a47f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_cb24294c-b2b8-4c0e-9897-8e83bf0f2e76" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_1a0f4ac3-251a-4f38-927d-f5a4129e3bb8" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_cb24294c-b2b8-4c0e-9897-8e83bf0f2e76" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3e65ba39-6e86-4d88-99d3-c0b97d8c3eb3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_1a0f4ac3-251a-4f38-927d-f5a4129e3bb8" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3e65ba39-6e86-4d88-99d3-c0b97d8c3eb3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_2cacb9eb-c9aa-416e-881c-b8b81851ae3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3e65ba39-6e86-4d88-99d3-c0b97d8c3eb3" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_2cacb9eb-c9aa-416e-881c-b8b81851ae3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_2cacb9eb-c9aa-416e-881c-b8b81851ae3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2cacb9eb-c9aa-416e-881c-b8b81851ae3c" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_2cacb9eb-c9aa-416e-881c-b8b81851ae3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_8b3c1a7e-e473-4d0e-9d05-916b799a4f41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2cacb9eb-c9aa-416e-881c-b8b81851ae3c" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_8b3c1a7e-e473-4d0e-9d05-916b799a4f41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsMember_361b3c32-c118-49a0-a174-62cf6ab06cf6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_8b3c1a7e-e473-4d0e-9d05-916b799a4f41" xlink:to="loc_us-gaap_CashEquivalentsMember_361b3c32-c118-49a0-a174-62cf6ab06cf6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShortTermMarketableSecuritiesMember_4cc9f5cd-e20c-472f-ab10-4ec6851a7798" xlink:href="cart-20230930.xsd#cart_ShortTermMarketableSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_8b3c1a7e-e473-4d0e-9d05-916b799a4f41" xlink:to="loc_cart_ShortTermMarketableSecuritiesMember_4cc9f5cd-e20c-472f-ab10-4ec6851a7798" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_LongTermMarketableSecuritiesMember_0ce600e8-6784-4f15-8961-d71406cabb96" xlink:href="cart-20230930.xsd#cart_LongTermMarketableSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_8b3c1a7e-e473-4d0e-9d05-916b799a4f41" xlink:to="loc_cart_LongTermMarketableSecuritiesMember_0ce600e8-6784-4f15-8961-d71406cabb96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_4c7e1399-133d-4757-82ff-992f0551ff38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3e65ba39-6e86-4d88-99d3-c0b97d8c3eb3" xlink:to="loc_us-gaap_FinancialInstrumentAxis_4c7e1399-133d-4757-82ff-992f0551ff38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4c7e1399-133d-4757-82ff-992f0551ff38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_4c7e1399-133d-4757-82ff-992f0551ff38" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4c7e1399-133d-4757-82ff-992f0551ff38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_85dce32d-0993-4b9f-b2e9-4098504e937e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_4c7e1399-133d-4757-82ff-992f0551ff38" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_85dce32d-0993-4b9f-b2e9-4098504e937e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_932d883b-b946-46fa-b9fe-4121f204389f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_85dce32d-0993-4b9f-b2e9-4098504e937e" xlink:to="loc_us-gaap_MoneyMarketFundsMember_932d883b-b946-46fa-b9fe-4121f204389f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_9bf1cbc9-ed2d-4d1d-b9b3-061e0e74caa2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_85dce32d-0993-4b9f-b2e9-4098504e937e" xlink:to="loc_us-gaap_CommercialPaperMember_9bf1cbc9-ed2d-4d1d-b9b3-061e0e74caa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_949973f0-e8ab-47a2-b2ec-a9898ec9d35b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_85dce32d-0993-4b9f-b2e9-4098504e937e" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_949973f0-e8ab-47a2-b2ec-a9898ec9d35b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_1be37ec2-a35d-422b-b492-d9671f9c530a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_85dce32d-0993-4b9f-b2e9-4098504e937e" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_1be37ec2-a35d-422b-b492-d9671f9c530a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/InvestmentsInvestmentsClassifiedbyContractualMaturityDateDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#InvestmentsInvestmentsClassifiedbyContractualMaturityDateDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/InvestmentsInvestmentsClassifiedbyContractualMaturityDateDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_28d1e15d-4df3-4dc9-89a8-1ca912346039" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_929da5ba-487a-43ef-b863-b6e07cd09fc3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_28d1e15d-4df3-4dc9-89a8-1ca912346039" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_929da5ba-487a-43ef-b863-b6e07cd09fc3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_c7e0181a-d105-4c53-99fa-a6513aefa470" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_28d1e15d-4df3-4dc9-89a8-1ca912346039" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_c7e0181a-d105-4c53-99fa-a6513aefa470" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_c331e0f6-59ad-45e1-b309-2f71dd21a80e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_28d1e15d-4df3-4dc9-89a8-1ca912346039" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_c331e0f6-59ad-45e1-b309-2f71dd21a80e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_e26a3f67-81c5-4245-870a-332ec192b9fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_28d1e15d-4df3-4dc9-89a8-1ca912346039" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_e26a3f67-81c5-4245-870a-332ec192b9fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_40912877-be00-49da-bbeb-787d38f9fd81" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_28d1e15d-4df3-4dc9-89a8-1ca912346039" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_40912877-be00-49da-bbeb-787d38f9fd81" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_5fe2903a-844d-4a76-8737-89551767fbea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_28d1e15d-4df3-4dc9-89a8-1ca912346039" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_5fe2903a-844d-4a76-8737-89551767fbea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_7c272121-cd52-499c-8c95-a6f5ac5daf3a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_28d1e15d-4df3-4dc9-89a8-1ca912346039" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_7c272121-cd52-499c-8c95-a6f5ac5daf3a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_64d6a85e-ab09-41fc-a573-c5bee7ad5e7e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_7c272121-cd52-499c-8c95-a6f5ac5daf3a" xlink:to="loc_srt_RangeAxis_64d6a85e-ab09-41fc-a573-c5bee7ad5e7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_64d6a85e-ab09-41fc-a573-c5bee7ad5e7e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_64d6a85e-ab09-41fc-a573-c5bee7ad5e7e" xlink:to="loc_srt_RangeMember_64d6a85e-ab09-41fc-a573-c5bee7ad5e7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b329ca77-4fbb-4c94-bff0-1e110e4fb2b2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_64d6a85e-ab09-41fc-a573-c5bee7ad5e7e" xlink:to="loc_srt_RangeMember_b329ca77-4fbb-4c94-bff0-1e110e4fb2b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_c88d438a-4ca2-422f-bd0d-72b711042e47" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_7c272121-cd52-499c-8c95-a6f5ac5daf3a" xlink:to="loc_us-gaap_FinancialInstrumentAxis_c88d438a-4ca2-422f-bd0d-72b711042e47" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_c88d438a-4ca2-422f-bd0d-72b711042e47_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_c88d438a-4ca2-422f-bd0d-72b711042e47" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_c88d438a-4ca2-422f-bd0d-72b711042e47_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bce3cc17-4124-4b2c-b4a5-ef734e57adbc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_c88d438a-4ca2-422f-bd0d-72b711042e47" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bce3cc17-4124-4b2c-b4a5-ef734e57adbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_aae922d2-35e5-4d4d-ae90-2156ac2f0b14" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bce3cc17-4124-4b2c-b4a5-ef734e57adbc" xlink:to="loc_us-gaap_CommercialPaperMember_aae922d2-35e5-4d4d-ae90-2156ac2f0b14" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_6c13018c-fcf5-4654-a600-30535018ffb4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bce3cc17-4124-4b2c-b4a5-ef734e57adbc" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_6c13018c-fcf5-4654-a600-30535018ffb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_6c41e9eb-3d30-46de-bd4f-ec89e92f4211" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bce3cc17-4124-4b2c-b4a5-ef734e57adbc" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_6c41e9eb-3d30-46de-bd4f-ec89e92f4211" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/PropertyandEquipmentNetPropertyandEquipmentNetofAccumulatedDepreciationandAmortizationDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#PropertyandEquipmentNetPropertyandEquipmentNetofAccumulatedDepreciationandAmortizationDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/PropertyandEquipmentNetPropertyandEquipmentNetofAccumulatedDepreciationandAmortizationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e957170c-16eb-4333-8a68-29899c9210a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_946c5269-acd1-499f-b784-1594e2c2d04a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e957170c-16eb-4333-8a68-29899c9210a4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_946c5269-acd1-499f-b784-1594e2c2d04a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_21e9a70f-95ad-4322-b813-57650f9bab36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e957170c-16eb-4333-8a68-29899c9210a4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_21e9a70f-95ad-4322-b813-57650f9bab36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_8a68caa3-a3e8-4970-889e-84efce2857c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e957170c-16eb-4333-8a68-29899c9210a4" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_8a68caa3-a3e8-4970-889e-84efce2857c4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_bbbfe8c5-c8e2-4034-a18b-cf6cc3189ee4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e957170c-16eb-4333-8a68-29899c9210a4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_bbbfe8c5-c8e2-4034-a18b-cf6cc3189ee4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_fe07983b-3f47-4016-9f8e-99cbe7ec9d45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e957170c-16eb-4333-8a68-29899c9210a4" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_fe07983b-3f47-4016-9f8e-99cbe7ec9d45" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_0e450653-09f1-4372-a06c-77c16928f4f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_fe07983b-3f47-4016-9f8e-99cbe7ec9d45" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_0e450653-09f1-4372-a06c-77c16928f4f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0e450653-09f1-4372-a06c-77c16928f4f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_0e450653-09f1-4372-a06c-77c16928f4f1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0e450653-09f1-4372-a06c-77c16928f4f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b815bd7e-8dcf-4395-8522-66be6a9e1416" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_0e450653-09f1-4372-a06c-77c16928f4f1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b815bd7e-8dcf-4395-8522-66be6a9e1416" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_92e2bbd9-fcb1-4436-8039-24adf1af81f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b815bd7e-8dcf-4395-8522-66be6a9e1416" xlink:to="loc_us-gaap_ComputerEquipmentMember_92e2bbd9-fcb1-4436-8039-24adf1af81f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_42fb517c-96b5-4a4d-9b89-6ff7162d8453" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b815bd7e-8dcf-4395-8522-66be6a9e1416" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_42fb517c-96b5-4a4d-9b89-6ff7162d8453" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_eebc0ed6-7b69-4454-83f9-279282442241" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b815bd7e-8dcf-4395-8522-66be6a9e1416" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_eebc0ed6-7b69-4454-83f9-279282442241" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_83fbd03c-0b76-4c56-a5c1-5fba94b418db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b815bd7e-8dcf-4395-8522-66be6a9e1416" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_83fbd03c-0b76-4c56-a5c1-5fba94b418db" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_4e174853-f66d-446f-9d24-d84f9e378bfd" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_fe07983b-3f47-4016-9f8e-99cbe7ec9d45" xlink:to="loc_srt_RangeAxis_4e174853-f66d-446f-9d24-d84f9e378bfd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4e174853-f66d-446f-9d24-d84f9e378bfd_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_4e174853-f66d-446f-9d24-d84f9e378bfd" xlink:to="loc_srt_RangeMember_4e174853-f66d-446f-9d24-d84f9e378bfd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_edf7ed75-5ec6-4f01-b3e3-c3c7a4d814b8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_4e174853-f66d-446f-9d24-d84f9e378bfd" xlink:to="loc_srt_RangeMember_edf7ed75-5ec6-4f01-b3e3-c3c7a4d814b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_71d8865d-cf48-4b5b-9e04-75e2799ca1ca" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_edf7ed75-5ec6-4f01-b3e3-c3c7a4d814b8" xlink:to="loc_srt_MinimumMember_71d8865d-cf48-4b5b-9e04-75e2799ca1ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ba2d4bc3-d481-4ee6-8464-4bc79af3797c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_edf7ed75-5ec6-4f01-b3e3-c3c7a4d814b8" xlink:to="loc_srt_MaximumMember_ba2d4bc3-d481-4ee6-8464-4bc79af3797c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/PropertyandEquipmentNetNarrativeDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#PropertyandEquipmentNetNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/PropertyandEquipmentNetNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_aa662b95-c4d2-4e3c-9e19-e0aaa3549d0a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_04f921c5-fbf7-40ac-a146-ed673c8958cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_aa662b95-c4d2-4e3c-9e19-e0aaa3549d0a" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_04f921c5-fbf7-40ac-a146-ed673c8958cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedComputerSoftwarePeriodIncreaseDecrease_1449ecdc-e05f-406c-a7d4-ced8305cd54e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalizedComputerSoftwarePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_aa662b95-c4d2-4e3c-9e19-e0aaa3549d0a" xlink:to="loc_us-gaap_CapitalizedComputerSoftwarePeriodIncreaseDecrease_1449ecdc-e05f-406c-a7d4-ced8305cd54e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_c876e3fb-08b8-439c-b4b2-d8a1c937b022" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_aa662b95-c4d2-4e3c-9e19-e0aaa3549d0a" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_c876e3fb-08b8-439c-b4b2-d8a1c937b022" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_7009903a-c52f-4585-a721-63786d7d2b59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_aa662b95-c4d2-4e3c-9e19-e0aaa3549d0a" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_7009903a-c52f-4585-a721-63786d7d2b59" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_ebe62870-e057-49da-b59b-28e567d5b651" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_7009903a-c52f-4585-a721-63786d7d2b59" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_ebe62870-e057-49da-b59b-28e567d5b651" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ebe62870-e057-49da-b59b-28e567d5b651_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_ebe62870-e057-49da-b59b-28e567d5b651" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_ebe62870-e057-49da-b59b-28e567d5b651_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2da6438-2699-4ea4-8d64-6247d245f0ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_ebe62870-e057-49da-b59b-28e567d5b651" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2da6438-2699-4ea4-8d64-6247d245f0ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentMember_d6e0018c-a5ce-41c2-8e14-8a14063dabc8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2da6438-2699-4ea4-8d64-6247d245f0ee" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentMember_d6e0018c-a5ce-41c2-8e14-8a14063dabc8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_d6b91960-aa64-4d85-9475-e1ecc6a68f27" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentMember_d6e0018c-a5ce-41c2-8e14-8a14063dabc8" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_d6b91960-aa64-4d85-9475-e1ecc6a68f27" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/PropertyandEquipmentNetLongLivedAssetsbyGeographicAreaDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#PropertyandEquipmentNetLongLivedAssetsbyGeographicAreaDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/PropertyandEquipmentNetLongLivedAssetsbyGeographicAreaDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_21b22de8-28bf-481f-a64c-81f358b9a855" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_PropertyPlantAndEquipmentAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_b7cadc3c-5241-48da-b830-75f9ddf879f6" xlink:href="cart-20230930.xsd#cart_PropertyPlantAndEquipmentAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_21b22de8-28bf-481f-a64c-81f358b9a855" xlink:to="loc_cart_PropertyPlantAndEquipmentAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_b7cadc3c-5241-48da-b830-75f9ddf879f6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_ae79cdbb-b335-4f8f-a153-c25ffc341639" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_21b22de8-28bf-481f-a64c-81f358b9a855" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_ae79cdbb-b335-4f8f-a153-c25ffc341639" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_78e303bd-5737-483c-93cd-8dd8d34f65fa" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_ae79cdbb-b335-4f8f-a153-c25ffc341639" xlink:to="loc_srt_StatementGeographicalAxis_78e303bd-5737-483c-93cd-8dd8d34f65fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_78e303bd-5737-483c-93cd-8dd8d34f65fa_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_78e303bd-5737-483c-93cd-8dd8d34f65fa" xlink:to="loc_srt_SegmentGeographicalDomain_78e303bd-5737-483c-93cd-8dd8d34f65fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_399e895e-23b6-4f5a-b4f2-a2351ab0c393" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_78e303bd-5737-483c-93cd-8dd8d34f65fa" xlink:to="loc_srt_SegmentGeographicalDomain_399e895e-23b6-4f5a-b4f2-a2351ab0c393" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_90f561a7-dadf-46f5-a969-ad07cbd201fa" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_399e895e-23b6-4f5a-b4f2-a2351ab0c393" xlink:to="loc_country_US_90f561a7-dadf-46f5-a969-ad07cbd201fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_e6e505c8-9ef5-458e-b992-77deccd19061" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_399e895e-23b6-4f5a-b4f2-a2351ab0c393" xlink:to="loc_country_CA_e6e505c8-9ef5-458e-b992-77deccd19061" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_OtherInternationalGeographiesMember_bc884437-cc17-40e9-8ba1-dc154e9aedca" xlink:href="cart-20230930.xsd#cart_OtherInternationalGeographiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_399e895e-23b6-4f5a-b4f2-a2351ab0c393" xlink:to="loc_cart_OtherInternationalGeographiesMember_bc884437-cc17-40e9-8ba1-dc154e9aedca" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/BusinessCombinationsNarrativeDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#BusinessCombinationsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/BusinessCombinationsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_0bf6acaf-863d-4bfc-a474-8a56b36e25f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_0bf6acaf-863d-4bfc-a474-8a56b36e25f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_d9dc70e7-5c60-4ae2-802a-d289f128ac25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_d9dc70e7-5c60-4ae2-802a-d289f128ac25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_623a3939-09f9-4250-944d-be72c7f2f798" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_623a3939-09f9-4250-944d-be72c7f2f798" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_a832435f-03e8-4ec7-bcfa-9e6f79bd89cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_a832435f-03e8-4ec7-bcfa-9e6f79bd89cb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_BusinessCombinationContingentConsiderationFairValue_a2e6f238-5682-4b90-aa0f-843a76b3ebac" xlink:href="cart-20230930.xsd#cart_BusinessCombinationContingentConsiderationFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_cart_BusinessCombinationContingentConsiderationFairValue_a2e6f238-5682-4b90-aa0f-843a76b3ebac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_f6764071-40d2-4caf-b249-f33569399fcc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_f6764071-40d2-4caf-b249-f33569399fcc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_4541f792-aaee-44e2-8152-e782cfaa6488" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_4541f792-aaee-44e2-8152-e782cfaa6488" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_7ac2b327-fc34-4cca-b949-b44909d4558b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_7ac2b327-fc34-4cca-b949-b44909d4558b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d689721e-701f-4193-9c8d-4e8c7de61f8f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f4bc21b1-0297-4388-b35f-cb408f9bae05" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d689721e-701f-4193-9c8d-4e8c7de61f8f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_cc296072-737d-4a5c-ba77-9936c46eb538" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d689721e-701f-4193-9c8d-4e8c7de61f8f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_cc296072-737d-4a5c-ba77-9936c46eb538" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_cc296072-737d-4a5c-ba77-9936c46eb538_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_cc296072-737d-4a5c-ba77-9936c46eb538" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_cc296072-737d-4a5c-ba77-9936c46eb538_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9e800aa-df4a-4e96-92ed-e70b71b6370a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_cc296072-737d-4a5c-ba77-9936c46eb538" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9e800aa-df4a-4e96-92ed-e70b71b6370a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_EversightMember_d4453bb1-6142-4968-b55e-8b3254fe3499" xlink:href="cart-20230930.xsd#cart_EversightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9e800aa-df4a-4e96-92ed-e70b71b6370a" xlink:to="loc_cart_EversightMember_d4453bb1-6142-4968-b55e-8b3254fe3499" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_RosieMember_bafce21e-6e1d-4fd2-bc87-e73cba595870" xlink:href="cart-20230930.xsd#cart_RosieMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9e800aa-df4a-4e96-92ed-e70b71b6370a" xlink:to="loc_cart_RosieMember_bafce21e-6e1d-4fd2-bc87-e73cba595870" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/BusinessCombinationsFairValueofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#BusinessCombinationsFairValueofAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/BusinessCombinationsFairValueofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_99cc84a5-8753-4a71-9f4e-f69cc8abe27e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_240aad11-26f9-4543-a735-ba4d3c66230b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_99cc84a5-8753-4a71-9f4e-f69cc8abe27e" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_240aad11-26f9-4543-a735-ba4d3c66230b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_0f6feca1-eff2-4f5f-8284-0124b2985da6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_99cc84a5-8753-4a71-9f4e-f69cc8abe27e" xlink:to="loc_us-gaap_Goodwill_0f6feca1-eff2-4f5f-8284-0124b2985da6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_c479bc2b-43a2-4f7e-84da-aab4c2a51dbc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_99cc84a5-8753-4a71-9f4e-f69cc8abe27e" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_c479bc2b-43a2-4f7e-84da-aab4c2a51dbc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAcquiredIncludingGoodwill_3e99f9e8-4967-4cf0-b303-fc9617b2e086" xlink:href="cart-20230930.xsd#cart_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAcquiredIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_99cc84a5-8753-4a71-9f4e-f69cc8abe27e" xlink:to="loc_cart_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAcquiredIncludingGoodwill_3e99f9e8-4967-4cf0-b303-fc9617b2e086" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_bb610a6c-e74e-4005-915c-a3ccd5b98932" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_99cc84a5-8753-4a71-9f4e-f69cc8abe27e" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_bb610a6c-e74e-4005-915c-a3ccd5b98932" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_0b346f34-6a9f-4d9e-96b6-6b8067f62350" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_99cc84a5-8753-4a71-9f4e-f69cc8abe27e" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_0b346f34-6a9f-4d9e-96b6-6b8067f62350" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_26629080-08fa-4e56-9c05-dd490b41600a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_99cc84a5-8753-4a71-9f4e-f69cc8abe27e" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_26629080-08fa-4e56-9c05-dd490b41600a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_2c5821df-73b7-4b3c-ac17-c39af7d2acc2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_26629080-08fa-4e56-9c05-dd490b41600a" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_2c5821df-73b7-4b3c-ac17-c39af7d2acc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2c5821df-73b7-4b3c-ac17-c39af7d2acc2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2c5821df-73b7-4b3c-ac17-c39af7d2acc2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2c5821df-73b7-4b3c-ac17-c39af7d2acc2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1d38c20c-c0ce-472d-961b-4f3f30c8d833" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2c5821df-73b7-4b3c-ac17-c39af7d2acc2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1d38c20c-c0ce-472d-961b-4f3f30c8d833" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_EversightMember_ff6e6858-f704-42f8-91f5-a8102eb91f2a" xlink:href="cart-20230930.xsd#cart_EversightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1d38c20c-c0ce-472d-961b-4f3f30c8d833" xlink:to="loc_cart_EversightMember_ff6e6858-f704-42f8-91f5-a8102eb91f2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_RosieMember_639bf569-7cc4-4777-8def-d10be1717fff" xlink:href="cart-20230930.xsd#cart_RosieMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1d38c20c-c0ce-472d-961b-4f3f30c8d833" xlink:to="loc_cart_RosieMember_639bf569-7cc4-4777-8def-d10be1717fff" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/BusinessCombinationsFairValueofIdentifiedIntangibleAssetsDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#BusinessCombinationsFairValueofIdentifiedIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/BusinessCombinationsFairValueofIdentifiedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_01b1d59d-a63c-4aa4-b6f5-b92b425b69b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_1134fc1c-9d39-47be-ae64-07c731a56204" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_01b1d59d-a63c-4aa4-b6f5-b92b425b69b6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_1134fc1c-9d39-47be-ae64-07c731a56204" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_ceaae966-72fa-425f-b539-c051ba49262e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_01b1d59d-a63c-4aa4-b6f5-b92b425b69b6" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_ceaae966-72fa-425f-b539-c051ba49262e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a9e466c-7bf2-44a7-83c8-13d141c93c52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_01b1d59d-a63c-4aa4-b6f5-b92b425b69b6" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a9e466c-7bf2-44a7-83c8-13d141c93c52" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_8f7b9287-8fa7-460b-8bb3-b6639bdd5aeb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a9e466c-7bf2-44a7-83c8-13d141c93c52" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_8f7b9287-8fa7-460b-8bb3-b6639bdd5aeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8f7b9287-8fa7-460b-8bb3-b6639bdd5aeb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_8f7b9287-8fa7-460b-8bb3-b6639bdd5aeb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8f7b9287-8fa7-460b-8bb3-b6639bdd5aeb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_12800153-4120-496e-b2dd-4123bde8111f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_8f7b9287-8fa7-460b-8bb3-b6639bdd5aeb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_12800153-4120-496e-b2dd-4123bde8111f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_EversightMember_dbad4966-771d-48c3-acdf-890f0ee3ac9d" xlink:href="cart-20230930.xsd#cart_EversightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_12800153-4120-496e-b2dd-4123bde8111f" xlink:to="loc_cart_EversightMember_dbad4966-771d-48c3-acdf-890f0ee3ac9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_RosieMember_959d8403-c484-4cc4-a19c-fba1ac41fce8" xlink:href="cart-20230930.xsd#cart_RosieMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_12800153-4120-496e-b2dd-4123bde8111f" xlink:to="loc_cart_RosieMember_959d8403-c484-4cc4-a19c-fba1ac41fce8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bc6d85b4-9112-454d-9150-2a30702a096d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a9e466c-7bf2-44a7-83c8-13d141c93c52" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bc6d85b4-9112-454d-9150-2a30702a096d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_bc6d85b4-9112-454d-9150-2a30702a096d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bc6d85b4-9112-454d-9150-2a30702a096d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_bc6d85b4-9112-454d-9150-2a30702a096d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8c6bc9fb-0f01-4c77-888f-1dac7bb6a934" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bc6d85b4-9112-454d-9150-2a30702a096d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8c6bc9fb-0f01-4c77-888f-1dac7bb6a934" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_4eb53317-421d-4587-bfc8-4fe1def50642" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8c6bc9fb-0f01-4c77-888f-1dac7bb6a934" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_4eb53317-421d-4587-bfc8-4fe1def50642" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_02f93ec1-8664-4f34-9200-1281bd86dc87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8c6bc9fb-0f01-4c77-888f-1dac7bb6a934" xlink:to="loc_us-gaap_CustomerRelationshipsMember_02f93ec1-8664-4f34-9200-1281bd86dc87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksMember_3243c0c6-3f59-46d5-876c-42fdbee9418d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TrademarksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8c6bc9fb-0f01-4c77-888f-1dac7bb6a934" xlink:to="loc_us-gaap_TrademarksMember_3243c0c6-3f59-46d5-876c-42fdbee9418d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_251844e0-5d07-4592-8628-7e631f184b2b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncompeteAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8c6bc9fb-0f01-4c77-888f-1dac7bb6a934" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_251844e0-5d07-4592-8628-7e631f184b2b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/GoodwillandIntangibleAssetsNetIntangibleAssetsNetDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#GoodwillandIntangibleAssetsNetIntangibleAssetsNetDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/GoodwillandIntangibleAssetsNetIntangibleAssetsNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_19d8bcb0-654f-47d0-9b46-8a673f57f119" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_03fcb9c7-33d1-43c3-8165-e2062ffc6d1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_19d8bcb0-654f-47d0-9b46-8a673f57f119" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_03fcb9c7-33d1-43c3-8165-e2062ffc6d1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_fba4e51c-a2b5-4cda-94e3-62b47d8f8658" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_19d8bcb0-654f-47d0-9b46-8a673f57f119" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_fba4e51c-a2b5-4cda-94e3-62b47d8f8658" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_56fd8030-1f10-4f83-9f92-5e8bd20c1cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_19d8bcb0-654f-47d0-9b46-8a673f57f119" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_56fd8030-1f10-4f83-9f92-5e8bd20c1cb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_5dbf8b86-29b2-4e61-93ba-7aa120c0b691" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_19d8bcb0-654f-47d0-9b46-8a673f57f119" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_5dbf8b86-29b2-4e61-93ba-7aa120c0b691" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_195e253c-91c7-451c-a6a1-db7ec69fe550" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_19d8bcb0-654f-47d0-9b46-8a673f57f119" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_195e253c-91c7-451c-a6a1-db7ec69fe550" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_fbe411f0-65f6-4f0a-a255-654288292c2e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_195e253c-91c7-451c-a6a1-db7ec69fe550" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_fbe411f0-65f6-4f0a-a255-654288292c2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_fbe411f0-65f6-4f0a-a255-654288292c2e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_fbe411f0-65f6-4f0a-a255-654288292c2e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_fbe411f0-65f6-4f0a-a255-654288292c2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f431d865-9588-437e-b6b3-8541430c6734" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_fbe411f0-65f6-4f0a-a255-654288292c2e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f431d865-9588-437e-b6b3-8541430c6734" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_f6b81feb-6276-40ee-b3ca-21c45045ed2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f431d865-9588-437e-b6b3-8541430c6734" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_f6b81feb-6276-40ee-b3ca-21c45045ed2f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_f815f264-098d-4604-a7ba-dc74832a74e5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f431d865-9588-437e-b6b3-8541430c6734" xlink:to="loc_us-gaap_CustomerRelationshipsMember_f815f264-098d-4604-a7ba-dc74832a74e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PatentsMember_049b6c0f-766b-4c6f-be02-a00f9d331840" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PatentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f431d865-9588-437e-b6b3-8541430c6734" xlink:to="loc_us-gaap_PatentsMember_049b6c0f-766b-4c6f-be02-a00f9d331840" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_b8746871-0454-4ff5-9d0f-6fd48c8beac5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f431d865-9588-437e-b6b3-8541430c6734" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_b8746871-0454-4ff5-9d0f-6fd48c8beac5" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_f4b9f69f-b4dd-4fb2-b8db-2a7948553e83" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_f4b9f69f-b4dd-4fb2-b8db-2a7948553e83" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_e69f470d-ae50-4300-87b1-92936dd44159" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_e69f470d-ae50-4300-87b1-92936dd44159" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_LesseeOperatingLeaseTerminateTerm_944fd84a-2623-41b9-ab79-5c1eb76416d9" xlink:href="cart-20230930.xsd#cart_LesseeOperatingLeaseTerminateTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_cart_LesseeOperatingLeaseTerminateTerm_944fd84a-2623-41b9-ab79-5c1eb76416d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued_8579bf63-7179-426f-8822-729d81833877" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued_8579bf63-7179-426f-8822-729d81833877" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_IncomeTaxesPotentialTaxInterestOrPenaltiesIncreaseDecreaseInReserveAmount_6d6d7605-1f0e-4e1c-a087-3df7a2344b99" xlink:href="cart-20230930.xsd#cart_IncomeTaxesPotentialTaxInterestOrPenaltiesIncreaseDecreaseInReserveAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_cart_IncomeTaxesPotentialTaxInterestOrPenaltiesIncreaseDecreaseInReserveAmount_6d6d7605-1f0e-4e1c-a087-3df7a2344b99" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_IncomeTaxesPotentialTaxClosingOfSaleAndUseTaxExaminationIncreaseDecreaseInReserveAmount_e5138717-8589-4192-9b27-c827cd3a6282" xlink:href="cart-20230930.xsd#cart_IncomeTaxesPotentialTaxClosingOfSaleAndUseTaxExaminationIncreaseDecreaseInReserveAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_cart_IncomeTaxesPotentialTaxClosingOfSaleAndUseTaxExaminationIncreaseDecreaseInReserveAmount_e5138717-8589-4192-9b27-c827cd3a6282" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_b153c2c6-1ae8-43ba-8c82-34c9c61a9a46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_b153c2c6-1ae8-43ba-8c82-34c9c61a9a46" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyLossInPeriod_04f9632e-5576-4ffb-8947-71b79922faf3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyLossInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_us-gaap_LossContingencyLossInPeriod_04f9632e-5576-4ffb-8947-71b79922faf3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_77dec581-8492-435f-99d0-0c0c4e767f3a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_77dec581-8492-435f-99d0-0c0c4e767f3a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_20c5a4d4-483a-43f6-91dc-e88c6ed13ab7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_20c5a4d4-483a-43f6-91dc-e88c6ed13ab7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_c368bab3-56b6-43c2-9070-920ad7efa5c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_c79e2921-40fa-4e5e-8da6-0ab94a76230c" xlink:to="loc_us-gaap_LossContingenciesTable_c368bab3-56b6-43c2-9070-920ad7efa5c0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_eb08d3d2-fc77-479c-b084-4f3d3e3f46b9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_c368bab3-56b6-43c2-9070-920ad7efa5c0" xlink:to="loc_srt_RangeAxis_eb08d3d2-fc77-479c-b084-4f3d3e3f46b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_eb08d3d2-fc77-479c-b084-4f3d3e3f46b9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_eb08d3d2-fc77-479c-b084-4f3d3e3f46b9" xlink:to="loc_srt_RangeMember_eb08d3d2-fc77-479c-b084-4f3d3e3f46b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_310b0316-6cd5-473a-870b-589669409b72" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_eb08d3d2-fc77-479c-b084-4f3d3e3f46b9" xlink:to="loc_srt_RangeMember_310b0316-6cd5-473a-870b-589669409b72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f92ff7a6-7d1c-411b-b762-f4eb44d3d683" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_310b0316-6cd5-473a-870b-589669409b72" xlink:to="loc_srt_MinimumMember_f92ff7a6-7d1c-411b-b762-f4eb44d3d683" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_3f7cbe62-675c-4065-81ce-cdd9ed88aca2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_310b0316-6cd5-473a-870b-589669409b72" xlink:to="loc_srt_MaximumMember_3f7cbe62-675c-4065-81ce-cdd9ed88aca2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/RedeemableConvertiblePreferredStockNarrativeDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#RedeemableConvertiblePreferredStockNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/RedeemableConvertiblePreferredStockNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_170bb3e1-ea1a-4a67-b502-f7e48b949c53" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_170bb3e1-ea1a-4a67-b502-f7e48b949c53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_4215e1bf-d85e-4592-9e01-3fd5d81a67f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_4215e1bf-d85e-4592-9e01-3fd5d81a67f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_906319f5-f6fb-493c-aab0-c4ed3e25bade" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_906319f5-f6fb-493c-aab0-c4ed3e25bade" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_1f97c99b-5199-41c2-a4a9-b74e82ea4285" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_1f97c99b-5199-41c2-a4a9-b74e82ea4285" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_f676c0df-7096-431b-8a44-d9ade4f102d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_f676c0df-7096-431b-8a44-d9ade4f102d1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_1dec52c1-c4f6-4e9d-8959-ea0708c26d6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_1dec52c1-c4f6-4e9d-8959-ea0708c26d6e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice_99dc08c7-3272-4400-858e-8cf975226bae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_SharePrice_99dc08c7-3272-4400-858e-8cf975226bae" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockExpectedTerm_0580afc3-5a39-4deb-84be-a0e49790b239" xlink:href="cart-20230930.xsd#cart_SaleOfStockExpectedTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_cart_SaleOfStockExpectedTerm_0580afc3-5a39-4deb-84be-a0e49790b239" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockVolatilityRate_15218b55-eaae-43b0-bd23-6010caeb940c" xlink:href="cart-20230930.xsd#cart_SaleOfStockVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_cart_SaleOfStockVolatilityRate_15218b55-eaae-43b0-bd23-6010caeb940c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockDiscountForLackOfMarketability_7e3d1ef6-9763-459a-9111-6520ef4726be" xlink:href="cart-20230930.xsd#cart_SaleOfStockDiscountForLackOfMarketability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_cart_SaleOfStockDiscountForLackOfMarketability_7e3d1ef6-9763-459a-9111-6520ef4726be" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SaleOfStockDividendRateApprovalThreshold_ccfd52fa-be85-4635-8b2e-476f7eeec138" xlink:href="cart-20230930.xsd#cart_SaleOfStockDividendRateApprovalThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_cart_SaleOfStockDividendRateApprovalThreshold_ccfd52fa-be85-4635-8b2e-476f7eeec138" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_VolumeWeightedAveragePriceMeasuringPeriod_7afaf913-2c5c-4d4c-ad44-d6d8dd9bbcf3" xlink:href="cart-20230930.xsd#cart_VolumeWeightedAveragePriceMeasuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_cart_VolumeWeightedAveragePriceMeasuringPeriod_7afaf913-2c5c-4d4c-ad44-d6d8dd9bbcf3" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_VolumeWeightedAveragePriceConsecutiveTradingDays_4d2627bc-e27a-4847-97fc-c0f13eb3535b" xlink:href="cart-20230930.xsd#cart_VolumeWeightedAveragePriceConsecutiveTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_cart_VolumeWeightedAveragePriceConsecutiveTradingDays_4d2627bc-e27a-4847-97fc-c0f13eb3535b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_aff454eb-2be3-4f2c-b4e9-907104ce6578" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_Dividends_aff454eb-2be3-4f2c-b4e9-907104ce6578" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_048a5e7d-fdc2-4fc4-8274-753b6e5a2afd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_268178a6-3eee-4cae-afee-1decc89b618b" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_048a5e7d-fdc2-4fc4-8274-753b6e5a2afd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_44bc50e4-0830-4d3d-9ef4-20ba5c0622e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_048a5e7d-fdc2-4fc4-8274-753b6e5a2afd" xlink:to="loc_us-gaap_StatementClassOfStockAxis_44bc50e4-0830-4d3d-9ef4-20ba5c0622e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_44bc50e4-0830-4d3d-9ef4-20ba5c0622e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_44bc50e4-0830-4d3d-9ef4-20ba5c0622e4" xlink:to="loc_us-gaap_ClassOfStockDomain_44bc50e4-0830-4d3d-9ef4-20ba5c0622e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7c95ec68-b12e-4232-b18f-c14fb2158c60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_44bc50e4-0830-4d3d-9ef4-20ba5c0622e4" xlink:to="loc_us-gaap_ClassOfStockDomain_7c95ec68-b12e-4232-b18f-c14fb2158c60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_b9942b60-e2a5-4027-b4ce-49cd56e0b33b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7c95ec68-b12e-4232-b18f-c14fb2158c60" xlink:to="loc_us-gaap_CommonStockMember_b9942b60-e2a5-4027-b4ce-49cd56e0b33b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_69e1e899-81d8-449d-a94c-948de4161b67" xlink:href="cart-20230930.xsd#cart_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7c95ec68-b12e-4232-b18f-c14fb2158c60" xlink:to="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_69e1e899-81d8-449d-a94c-948de4161b67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_598d0ac7-9e09-44c1-ad95-0b41884d10e5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_048a5e7d-fdc2-4fc4-8274-753b6e5a2afd" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_598d0ac7-9e09-44c1-ad95-0b41884d10e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_598d0ac7-9e09-44c1-ad95-0b41884d10e5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_598d0ac7-9e09-44c1-ad95-0b41884d10e5" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_598d0ac7-9e09-44c1-ad95-0b41884d10e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_a8a34b9e-90b3-4edd-ad52-66c21ab020aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_598d0ac7-9e09-44c1-ad95-0b41884d10e5" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_a8a34b9e-90b3-4edd-ad52-66c21ab020aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrivatePlacementMember_35ead4c9-7a9c-471b-9adf-e731797a549e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrivatePlacementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_a8a34b9e-90b3-4edd-ad52-66c21ab020aa" xlink:to="loc_us-gaap_PrivatePlacementMember_35ead4c9-7a9c-471b-9adf-e731797a549e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/RedeemableConvertiblePreferredStockScheduleofConvertiblePreferredStockDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#RedeemableConvertiblePreferredStockScheduleofConvertiblePreferredStockDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/RedeemableConvertiblePreferredStockScheduleofConvertiblePreferredStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesAuthorized_e7f65ebc-f431-4eea-aa6c-665cd03bd1a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:to="loc_us-gaap_TemporaryEquitySharesAuthorized_e7f65ebc-f431-4eea-aa6c-665cd03bd1a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued_3a230d79-fd1c-405f-9682-61bfedbecf37" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued_3a230d79-fd1c-405f-9682-61bfedbecf37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_7021d54c-eb2b-403a-b721-9b86954bbe93" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_7021d54c-eb2b-403a-b721-9b86954bbe93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_TemporaryEquityIssuancePricePerShare_0c766b94-b98c-4905-821e-0f367564cfa8" xlink:href="cart-20230930.xsd#cart_TemporaryEquityIssuancePricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:to="loc_cart_TemporaryEquityIssuancePricePerShare_0c766b94-b98c-4905-821e-0f367564cfa8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityRedemptionPricePerShare_74953f42-d4d8-4f77-97fd-899eb46feead" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityRedemptionPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:to="loc_us-gaap_TemporaryEquityRedemptionPricePerShare_74953f42-d4d8-4f77-97fd-899eb46feead" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_7be93c36-a660-42ec-b6a1-69b383740cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_7be93c36-a660-42ec-b6a1-69b383740cbc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityLiquidationPreference_dbd9c12f-293a-4212-93fd-bee883dfbb23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityLiquidationPreference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:to="loc_us-gaap_TemporaryEquityLiquidationPreference_dbd9c12f-293a-4212-93fd-bee883dfbb23" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_f7513025-51c5-40cc-811c-8348ada64750" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_f3ea1c49-ab6f-4f51-93e3-2fd53a84a2ee" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_f7513025-51c5-40cc-811c-8348ada64750" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_f0e0ffb9-084c-4eea-8ce2-965cb518ea68" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f7513025-51c5-40cc-811c-8348ada64750" xlink:to="loc_us-gaap_StatementClassOfStockAxis_f0e0ffb9-084c-4eea-8ce2-965cb518ea68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_f0e0ffb9-084c-4eea-8ce2-965cb518ea68_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_f0e0ffb9-084c-4eea-8ce2-965cb518ea68" xlink:to="loc_us-gaap_ClassOfStockDomain_f0e0ffb9-084c-4eea-8ce2-965cb518ea68_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_f0e0ffb9-084c-4eea-8ce2-965cb518ea68" xlink:to="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_0bd7e03f-1716-41b4-bb39-b031907c2998" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_0bd7e03f-1716-41b4-bb39-b031907c2998" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_d34bc6b3-9567-41e1-80b6-bd4682615cf1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_d34bc6b3-9567-41e1-80b6-bd4682615cf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesB1ConvertiblePreferredStockMember_478178ff-56df-4b79-8808-56e6eadebeec" xlink:href="cart-20230930.xsd#cart_SeriesB1ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_cart_SeriesB1ConvertiblePreferredStockMember_478178ff-56df-4b79-8808-56e6eadebeec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesCPreferredStockMember_e29e1fa4-9b5e-43bf-8bf1-f1dea6123f5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesCPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_us-gaap_SeriesCPreferredStockMember_e29e1fa4-9b5e-43bf-8bf1-f1dea6123f5d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesDPreferredStockMember_8055874f-155a-41e9-867c-eba34eb0cc76" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesDPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_us-gaap_SeriesDPreferredStockMember_8055874f-155a-41e9-867c-eba34eb0cc76" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesEPreferredStockMember_c3d55d07-4a54-4fe2-931b-9bc852559611" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesEPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_us-gaap_SeriesEPreferredStockMember_c3d55d07-4a54-4fe2-931b-9bc852559611" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesFPreferredStockMember_cb4e3857-e006-48ea-aa50-50c10e968d01" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesFPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_us-gaap_SeriesFPreferredStockMember_cb4e3857-e006-48ea-aa50-50c10e968d01" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesGPreferredStockMember_32fcab5e-ca82-4c8b-b3f0-7ba3eab7fe39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesGPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_us-gaap_SeriesGPreferredStockMember_32fcab5e-ca82-4c8b-b3f0-7ba3eab7fe39" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesHPreferredStockMember_64aa103a-75e8-4840-b91e-b777b50ef966" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesHPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_us-gaap_SeriesHPreferredStockMember_64aa103a-75e8-4840-b91e-b777b50ef966" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesIPreferredStockMember_78da03af-9fcd-437b-99ed-d5fc4e5a5b10" xlink:href="cart-20230930.xsd#cart_SeriesIPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_cart_SeriesIPreferredStockMember_78da03af-9fcd-437b-99ed-d5fc4e5a5b10" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesI1PreferredStockMember_f7e6f3d2-4e85-4771-8e36-d9053097bd0d" xlink:href="cart-20230930.xsd#cart_SeriesI1PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_38665e4b-38ed-496d-89b7-e84ed5602164" xlink:to="loc_cart_SeriesI1PreferredStockMember_f7e6f3d2-4e85-4771-8e36-d9053097bd0d" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofCommonStockReservedforFutureIssuanceDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#StockholdersEquityDeficitScheduleofCommonStockReservedforFutureIssuanceDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofCommonStockReservedforFutureIssuanceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_552ff5cd-0150-464a-9f7d-a41dd661c160" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_f31cfa38-adf9-41d7-b282-29afd422454b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_552ff5cd-0150-464a-9f7d-a41dd661c160" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_f31cfa38-adf9-41d7-b282-29afd422454b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_4b4d85cc-8ce8-4209-85ac-74cb035a779b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_552ff5cd-0150-464a-9f7d-a41dd661c160" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_4b4d85cc-8ce8-4209-85ac-74cb035a779b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_d0fb4fc1-63fa-4807-9bba-05c263fbc076" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_4b4d85cc-8ce8-4209-85ac-74cb035a779b" xlink:to="loc_us-gaap_AwardTypeAxis_d0fb4fc1-63fa-4807-9bba-05c263fbc076" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d0fb4fc1-63fa-4807-9bba-05c263fbc076_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_d0fb4fc1-63fa-4807-9bba-05c263fbc076" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d0fb4fc1-63fa-4807-9bba-05c263fbc076_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_d0fb4fc1-63fa-4807-9bba-05c263fbc076" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_9f535e18-c48a-4af4-b4cf-90827ad44a18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_9f535e18-c48a-4af4-b4cf-90827ad44a18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_edc7975f-535c-4431-83d6-ee3fc206012a" xlink:href="cart-20230930.xsd#cart_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:to="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_edc7975f-535c-4431-83d6-ee3fc206012a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_94efc189-638f-45e1-8486-60aa4c3c0080" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:to="loc_us-gaap_WarrantMember_94efc189-638f-45e1-8486-60aa4c3c0080" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_8714016c-2de0-49ae-8cae-ab0bb2f678ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_8714016c-2de0-49ae-8cae-ab0bb2f678ac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableSharesOutstandingMember_8f09c34c-bf11-4ba9-b6f2-dc801439bfdd" xlink:href="cart-20230930.xsd#cart_ExchangeableSharesOutstandingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:to="loc_cart_ExchangeableSharesOutstandingMember_8f09c34c-bf11-4ba9-b6f2-dc801439bfdd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_d89fac81-ca0a-49c1-82a5-69ec39069356" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:to="loc_us-gaap_EmployeeStockOptionMember_d89fac81-ca0a-49c1-82a5-69ec39069356" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SharesAvailableForFutureGrantMember_2a1ccc13-750b-44c2-88db-6d41a928b08c" xlink:href="cart-20230930.xsd#cart_SharesAvailableForFutureGrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:to="loc_cart_SharesAvailableForFutureGrantMember_2a1ccc13-750b-44c2-88db-6d41a928b08c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_0ffa7b00-6a0e-4da2-a359-f59c3032513a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0c10b796-fa5a-4804-801a-677e5226ab43" xlink:to="loc_us-gaap_EmployeeStockMember_0ffa7b00-6a0e-4da2-a359-f59c3032513a" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/StockholdersEquityDeficitNarrativeDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#StockholdersEquityDeficitNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/StockholdersEquityDeficitNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_c774b65b-ef84-45e9-8f62-33a5e77bed6c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_Dividends_c774b65b-ef84-45e9-8f62-33a5e77bed6c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_c63a3c0b-e796-40aa-9573-6f30168b131b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_c63a3c0b-e796-40aa-9573-6f30168b131b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_ee802c2c-d269-4843-8829-8cfe917671e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_ee802c2c-d269-4843-8829-8cfe917671e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_61d49289-7416-4494-b0f8-6f2864640666" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_61d49289-7416-4494-b0f8-6f2864640666" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumSharesIssuedUponExercise_81ac4b20-795c-4417-b760-d1ca73354c08" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumSharesIssuedUponExercise"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumSharesIssuedUponExercise_81ac4b20-795c-4417-b760-d1ca73354c08" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_ae1c2da0-cb22-4bbd-b81a-23c55767e90d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_ae1c2da0-cb22-4bbd-b81a-23c55767e90d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_36a666cc-d34b-48ca-8e76-f3d66546266a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_36a666cc-d34b-48ca-8e76-f3d66546266a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_90e50754-dba7-4b83-af2e-dc1c6a60f982" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_90e50754-dba7-4b83-af2e-dc1c6a60f982" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAllowableUnderThePlan_6ccdc227-b5b7-43d1-9221-8605cf837d39" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAllowableUnderThePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAllowableUnderThePlan_6ccdc227-b5b7-43d1-9221-8605cf837d39" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_f82de111-0257-4891-8cea-568aec0850ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_f82de111-0257-4891-8cea-568aec0850ef" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_d00e5b87-8e10-4fe1-b47c-94b0dce785ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_d00e5b87-8e10-4fe1-b47c-94b0dce785ec" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_3326ef50-f792-45d6-b89c-0cf40aeb04df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_3326ef50-f792-45d6-b89c-0cf40aeb04df" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_135aca39-d900-405b-8d05-e6a1f536c718" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_135aca39-d900-405b-8d05-e6a1f536c718" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_a2599d77-716c-467b-8992-2ad6d27432cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_333b3615-159a-4776-bb2e-1d056ebee9af" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_a2599d77-716c-467b-8992-2ad6d27432cf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_55298559-37e0-4e56-a4d4-fc59879cd590" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_a2599d77-716c-467b-8992-2ad6d27432cf" xlink:to="loc_us-gaap_AwardTypeAxis_55298559-37e0-4e56-a4d4-fc59879cd590" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55298559-37e0-4e56-a4d4-fc59879cd590_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_55298559-37e0-4e56-a4d4-fc59879cd590" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_55298559-37e0-4e56-a4d4-fc59879cd590_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a1e08a2f-d227-4613-8b8c-43fc58517700" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_55298559-37e0-4e56-a4d4-fc59879cd590" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a1e08a2f-d227-4613-8b8c-43fc58517700" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_47dcf222-a6bb-4859-91c5-e229d7a2b949" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a1e08a2f-d227-4613-8b8c-43fc58517700" xlink:to="loc_us-gaap_EmployeeStockOptionMember_47dcf222-a6bb-4859-91c5-e229d7a2b949" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_18ede8b2-19de-4975-9981-f257e0a0c12e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a1e08a2f-d227-4613-8b8c-43fc58517700" xlink:to="loc_us-gaap_EmployeeStockMember_18ede8b2-19de-4975-9981-f257e0a0c12e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_ff117685-12e0-4161-8e47-b4ca5e8843a8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a1e08a2f-d227-4613-8b8c-43fc58517700" xlink:to="loc_us-gaap_CommonStockMember_ff117685-12e0-4161-8e47-b4ca5e8843a8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_2639e0d7-615b-4d7a-818c-a55ca4bfe5da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_a2599d77-716c-467b-8992-2ad6d27432cf" xlink:to="loc_us-gaap_PlanNameAxis_2639e0d7-615b-4d7a-818c-a55ca4bfe5da" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_2639e0d7-615b-4d7a-818c-a55ca4bfe5da_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_2639e0d7-615b-4d7a-818c-a55ca4bfe5da" xlink:to="loc_us-gaap_PlanNameDomain_2639e0d7-615b-4d7a-818c-a55ca4bfe5da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_6215a8aa-8e96-4fb0-b254-87db1db42a98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_2639e0d7-615b-4d7a-818c-a55ca4bfe5da" xlink:to="loc_us-gaap_PlanNameDomain_6215a8aa-8e96-4fb0-b254-87db1db42a98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_A2023PlanMember_e012fc06-c240-4dcf-ad67-89f56ee74892" xlink:href="cart-20230930.xsd#cart_A2023PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_6215a8aa-8e96-4fb0-b254-87db1db42a98" xlink:to="loc_cart_A2023PlanMember_e012fc06-c240-4dcf-ad67-89f56ee74892" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofStockOptionsRollForwardDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#StockholdersEquityDeficitScheduleofStockOptionsRollForwardDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofStockOptionsRollForwardDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_9d8923fb-4183-419e-b519-f0589475528a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_9d8923fb-4183-419e-b519-f0589475528a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_3e18d242-839e-4403-9ee4-02b518b6a745" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_3e18d242-839e-4403-9ee4-02b518b6a745" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_752836a0-beb5-4e89-bf0e-a708f8173638" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_752836a0-beb5-4e89-bf0e-a708f8173638" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_e3423bfe-0e00-4444-bf33-2c0142b65c1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_e3423bfe-0e00-4444-bf33-2c0142b65c1a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesWithheldRelatedToNetShareSettlement_16704652-7040-46fc-82f0-d373994585e9" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesWithheldRelatedToNetShareSettlement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesWithheldRelatedToNetShareSettlement_16704652-7040-46fc-82f0-d373994585e9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_cd086a36-90a2-4b81-bb58-56ab0cb940ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_cd086a36-90a2-4b81-bb58-56ab0cb940ca" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_a8d9ca93-84b9-4765-81fa-ea2fc8954b12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsShareAvailableForFutureGrantRollForward_61a6aa66-985e-4e01-affb-8a0746865d71" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_a8d9ca93-84b9-4765-81fa-ea2fc8954b12" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_80e5b8ea-efce-4ae2-8bfe-deb18ffc3109" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_daa38329-a4b5-4101-a271-91d9c9aec3e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_daa38329-a4b5-4101-a271-91d9c9aec3e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_e854b4b9-141b-4f12-b1d0-b86eb411815d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_daa38329-a4b5-4101-a271-91d9c9aec3e2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_e854b4b9-141b-4f12-b1d0-b86eb411815d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_82bb137e-1d51-459d-8ce4-6a1c73707e6d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_daa38329-a4b5-4101-a271-91d9c9aec3e2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_82bb137e-1d51-459d-8ce4-6a1c73707e6d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_b2f31b90-be94-4e24-b476-cf2ba7f6cc3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_0717e90e-f1a8-405d-afbe-87cbf80cc0bc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_06d2b50b-623e-471c-a932-8f5d5fc306be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_06d2b50b-623e-471c-a932-8f5d5fc306be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_9929769a-02be-4864-90a4-659db23648ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_9929769a-02be-4864-90a4-659db23648ae" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_f2351b1b-2709-4740-87cb-97dafe8dbb39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_f2351b1b-2709-4740-87cb-97dafe8dbb39" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_8871d175-7d84-462c-9f4c-5420577edf7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_f2351b1b-2709-4740-87cb-97dafe8dbb39" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_8871d175-7d84-462c-9f4c-5420577edf7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_a4d63698-1439-4655-945a-f73b427c908d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_f2351b1b-2709-4740-87cb-97dafe8dbb39" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_a4d63698-1439-4655-945a-f73b427c908d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_85f92910-fb23-47db-be29-7e502e632d00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_f2351b1b-2709-4740-87cb-97dafe8dbb39" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_85f92910-fb23-47db-be29-7e502e632d00" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_da34f9c0-fd0a-4f4f-84b0-6288fd3e1805" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_da34f9c0-fd0a-4f4f-84b0-6288fd3e1805" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_6db1a14d-6cb2-49e3-b459-9ca22b6994a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_6db1a14d-6cb2-49e3-b459-9ca22b6994a9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_3a510fa1-5290-4f0b-b1ff-db9a233c82fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_3a510fa1-5290-4f0b-b1ff-db9a233c82fc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_12d8cb20-8c0d-47b6-9cdb-1945f946387e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_3a510fa1-5290-4f0b-b1ff-db9a233c82fc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_12d8cb20-8c0d-47b6-9cdb-1945f946387e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_2be2f3bd-c92f-4c25-9d3a-77dcf5dfe9fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_3a510fa1-5290-4f0b-b1ff-db9a233c82fc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_2be2f3bd-c92f-4c25-9d3a-77dcf5dfe9fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_ec11dc57-84a7-4987-b5d4-91a8e4839ba9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_3a510fa1-5290-4f0b-b1ff-db9a233c82fc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_ec11dc57-84a7-4987-b5d4-91a8e4839ba9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_9087e460-a7dc-43cc-922d-cb9edae6a67a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_3a510fa1-5290-4f0b-b1ff-db9a233c82fc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_9087e460-a7dc-43cc-922d-cb9edae6a67a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_5d2e7534-aa9d-496c-b90a-dc811758bf25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_3a510fa1-5290-4f0b-b1ff-db9a233c82fc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_5d2e7534-aa9d-496c-b90a-dc811758bf25" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_ab7b1aac-307d-48d1-848d-b4fe50cac059" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_3a510fa1-5290-4f0b-b1ff-db9a233c82fc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_ab7b1aac-307d-48d1-848d-b4fe50cac059" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_73a7815b-9d3c-4c18-90e4-22db82fcdf2b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ab487c63-8146-4e0a-8fa6-971f5f206952" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_73a7815b-9d3c-4c18-90e4-22db82fcdf2b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_6cb654bb-0518-424e-928e-40f90d80166b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_73a7815b-9d3c-4c18-90e4-22db82fcdf2b" xlink:to="loc_us-gaap_AwardTypeAxis_6cb654bb-0518-424e-928e-40f90d80166b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6cb654bb-0518-424e-928e-40f90d80166b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_6cb654bb-0518-424e-928e-40f90d80166b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6cb654bb-0518-424e-928e-40f90d80166b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24c283f4-d32b-440b-a734-8b2769bd3fe6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_6cb654bb-0518-424e-928e-40f90d80166b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24c283f4-d32b-440b-a734-8b2769bd3fe6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_4f303e5a-edad-44db-ba54-a02e16d00f3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24c283f4-d32b-440b-a734-8b2769bd3fe6" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_4f303e5a-edad-44db-ba54-a02e16d00f3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_859ca278-0f02-4eb6-a29f-4792280da2b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24c283f4-d32b-440b-a734-8b2769bd3fe6" xlink:to="loc_us-gaap_RestrictedStockMember_859ca278-0f02-4eb6-a29f-4792280da2b4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofNonvestedRestrictedStockSharesActivityDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#StockholdersEquityDeficitScheduleofNonvestedRestrictedStockSharesActivityDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofNonvestedRestrictedStockSharesActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_5c258f72-78d4-4196-aa60-a43c4a930cab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3cf8bb83-c794-4546-a77b-88637caf37ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5c258f72-78d4-4196-aa60-a43c4a930cab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3cf8bb83-c794-4546-a77b-88637caf37ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_7a221741-56bc-4bdb-a190-c69bf2670681" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3cf8bb83-c794-4546-a77b-88637caf37ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_7a221741-56bc-4bdb-a190-c69bf2670681" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_86ee04eb-5b2c-412e-a99b-2d4e675f5cad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3cf8bb83-c794-4546-a77b-88637caf37ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_86ee04eb-5b2c-412e-a99b-2d4e675f5cad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_493fb572-8a13-4194-ad6b-8ff8c8083128" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3cf8bb83-c794-4546-a77b-88637caf37ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_493fb572-8a13-4194-ad6b-8ff8c8083128" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares_5baaf997-9a09-410d-8d44-c47645b19663" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3cf8bb83-c794-4546-a77b-88637caf37ba" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares_5baaf997-9a09-410d-8d44-c47645b19663" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_db01d386-880c-4f7c-8e76-421d9b1f011b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1d9e1fbb-b500-4674-a013-ce4c6a46784c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5c258f72-78d4-4196-aa60-a43c4a930cab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1d9e1fbb-b500-4674-a013-ce4c6a46784c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_e2c751a7-619d-4a94-a7e3-ad715a427e7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1d9e1fbb-b500-4674-a013-ce4c6a46784c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_e2c751a7-619d-4a94-a7e3-ad715a427e7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8360bee2-52e6-4c35-af5e-66cca2a5c1b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1d9e1fbb-b500-4674-a013-ce4c6a46784c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8360bee2-52e6-4c35-af5e-66cca2a5c1b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f97c35e9-ec2e-4557-9bb2-cdf58cff645a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1d9e1fbb-b500-4674-a013-ce4c6a46784c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f97c35e9-ec2e-4557-9bb2-cdf58cff645a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_1b9b30ed-1041-42bd-bccb-dbc882da4043" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_1d9e1fbb-b500-4674-a013-ce4c6a46784c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_1b9b30ed-1041-42bd-bccb-dbc882da4043" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b3d47393-db1c-47a2-b817-b07180b994ce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_0035b90c-5744-4fe9-9b2f-30004d41ab68" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5c258f72-78d4-4196-aa60-a43c4a930cab" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_0035b90c-5744-4fe9-9b2f-30004d41ab68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_027f0339-1369-4e25-88d1-371b81f4bb3b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_5c258f72-78d4-4196-aa60-a43c4a930cab" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_027f0339-1369-4e25-88d1-371b81f4bb3b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_2e6fb9cf-b1c0-448b-9dfc-585e7fca8f62" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_027f0339-1369-4e25-88d1-371b81f4bb3b" xlink:to="loc_us-gaap_AwardTypeAxis_2e6fb9cf-b1c0-448b-9dfc-585e7fca8f62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2e6fb9cf-b1c0-448b-9dfc-585e7fca8f62_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2e6fb9cf-b1c0-448b-9dfc-585e7fca8f62" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2e6fb9cf-b1c0-448b-9dfc-585e7fca8f62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_099b7d3b-1899-40be-9c29-29dd34068346" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2e6fb9cf-b1c0-448b-9dfc-585e7fca8f62" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_099b7d3b-1899-40be-9c29-29dd34068346" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_5d3583b1-7a76-472f-969c-7c38a56d23f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_099b7d3b-1899-40be-9c29-29dd34068346" xlink:to="loc_us-gaap_RestrictedStockMember_5d3583b1-7a76-472f-969c-7c38a56d23f8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofNonvestedRestrictedStockUnitsActivityDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#StockholdersEquityDeficitScheduleofNonvestedRestrictedStockUnitsActivityDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofNonvestedRestrictedStockUnitsActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_1b44cb15-8593-4b7b-b922-a554bbb432dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6134583f-8ec6-4be9-9efa-5000fefaed2a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_1b44cb15-8593-4b7b-b922-a554bbb432dc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6134583f-8ec6-4be9-9efa-5000fefaed2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_a9c4b8ac-8205-40e0-b4c5-06b5ae93233e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6134583f-8ec6-4be9-9efa-5000fefaed2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_a9c4b8ac-8205-40e0-b4c5-06b5ae93233e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_f9060405-ac68-4fc4-b7ad-91d06de27348" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6134583f-8ec6-4be9-9efa-5000fefaed2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_f9060405-ac68-4fc4-b7ad-91d06de27348" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_3347f49f-b1ef-42cd-8796-6c2c8d34c425" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6134583f-8ec6-4be9-9efa-5000fefaed2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_3347f49f-b1ef-42cd-8796-6c2c8d34c425" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndNotSettledInPeriod_e05e2d55-b762-455e-818b-177cddcd8cd0" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndNotSettledInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6134583f-8ec6-4be9-9efa-5000fefaed2a" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndNotSettledInPeriod_e05e2d55-b762-455e-818b-177cddcd8cd0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_4d2dcb76-15ff-4aee-bdd8-61f327dc81ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6134583f-8ec6-4be9-9efa-5000fefaed2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_4d2dcb76-15ff-4aee-bdd8-61f327dc81ff" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_b21e5332-ff3c-4ea7-9366-4c67b3ef4188" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_8b72d664-c9d7-4485-a885-18faa169bf72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_1b44cb15-8593-4b7b-b922-a554bbb432dc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_8b72d664-c9d7-4485-a885-18faa169bf72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_5faf5064-f5d5-41c0-bfe3-e4f8f33cc7d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_8b72d664-c9d7-4485-a885-18faa169bf72" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_5faf5064-f5d5-41c0-bfe3-e4f8f33cc7d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_00b75215-0425-4593-ac50-220f0140a6eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_8b72d664-c9d7-4485-a885-18faa169bf72" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_00b75215-0425-4593-ac50-220f0140a6eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f4fd24f9-511a-4007-bdc6-3b2372c238ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_8b72d664-c9d7-4485-a885-18faa169bf72" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f4fd24f9-511a-4007-bdc6-3b2372c238ff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndNotSettledInPeriodWeightedAverageGrantDateFairValue_b8afb64e-3e0d-4f54-8ed6-0b8bf5ef85e5" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndNotSettledInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_8b72d664-c9d7-4485-a885-18faa169bf72" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndNotSettledInPeriodWeightedAverageGrantDateFairValue_b8afb64e-3e0d-4f54-8ed6-0b8bf5ef85e5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_0412c2fa-47e3-48a5-a662-181ea77cc94e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_8b72d664-c9d7-4485-a885-18faa169bf72" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_0412c2fa-47e3-48a5-a662-181ea77cc94e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_697688ef-5635-4af4-8abb-d704c6f6af60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_d51034ec-dd34-4d41-8919-a905d196ec07" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_1b44cb15-8593-4b7b-b922-a554bbb432dc" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_d51034ec-dd34-4d41-8919-a905d196ec07" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_36c3cb5c-181a-46e0-9490-5048d5dccb0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_1b44cb15-8593-4b7b-b922-a554bbb432dc" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_36c3cb5c-181a-46e0-9490-5048d5dccb0b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_db155a9f-2a7a-49ce-a24c-9aa02bfe0bd6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_36c3cb5c-181a-46e0-9490-5048d5dccb0b" xlink:to="loc_us-gaap_AwardTypeAxis_db155a9f-2a7a-49ce-a24c-9aa02bfe0bd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_db155a9f-2a7a-49ce-a24c-9aa02bfe0bd6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_db155a9f-2a7a-49ce-a24c-9aa02bfe0bd6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_db155a9f-2a7a-49ce-a24c-9aa02bfe0bd6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_08450a72-f80a-4854-b2ed-16bb06adc739" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_db155a9f-2a7a-49ce-a24c-9aa02bfe0bd6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_08450a72-f80a-4854-b2ed-16bb06adc739" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_74f41d19-725b-493f-916a-dad45bb87130" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_08450a72-f80a-4854-b2ed-16bb06adc739" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_74f41d19-725b-493f-916a-dad45bb87130" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofConversionsofStockDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#StockholdersEquityDeficitScheduleofConversionsofStockDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/StockholdersEquityDeficitScheduleofConversionsofStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_3a6cd3ca-bdb7-42f5-ac95-6b85b95a164b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_e60a06dd-1931-4971-a832-935dc4849c50" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_3a6cd3ca-bdb7-42f5-ac95-6b85b95a164b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_e60a06dd-1931-4971-a832-935dc4849c50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_3bece498-265e-47fc-8a65-1e115567a566" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_e60a06dd-1931-4971-a832-935dc4849c50" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_3bece498-265e-47fc-8a65-1e115567a566" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsIssuedInPeriod_5ab66269-f6db-4a52-a2b7-a33d0a20f6ba" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_e60a06dd-1931-4971-a832-935dc4849c50" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsIssuedInPeriod_5ab66269-f6db-4a52-a2b7-a33d0a20f6ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirations_8c4a5962-184b-4f27-8c8f-d8baa8d653f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_e60a06dd-1931-4971-a832-935dc4849c50" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirations_8c4a5962-184b-4f27-8c8f-d8baa8d653f7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsSharesExchangedInPeriod_d59b303a-8b4a-4d6c-acf6-508bea2f25f0" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsSharesExchangedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_e60a06dd-1931-4971-a832-935dc4849c50" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsSharesExchangedInPeriod_d59b303a-8b4a-4d6c-acf6-508bea2f25f0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_c913c95e-94b5-49f4-9759-cb564cc38998" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_0fe0e02a-91d5-4607-9833-e00a647c0374" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_3a6cd3ca-bdb7-42f5-ac95-6b85b95a164b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_0fe0e02a-91d5-4607-9833-e00a647c0374" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice_b6b2f920-1864-4925-8d13-dfa16e023c09" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_0fe0e02a-91d5-4607-9833-e00a647c0374" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice_b6b2f920-1864-4925-8d13-dfa16e023c09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsIssuedInPeriodWeightedAverageExercisePrice_114ed43f-d787-4d0b-af86-72d1fbbc5bed" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsIssuedInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_0fe0e02a-91d5-4607-9833-e00a647c0374" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsIssuedInPeriodWeightedAverageExercisePrice_114ed43f-d787-4d0b-af86-72d1fbbc5bed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirationsWeightedAverageExercisePrice_41f01067-921d-4741-bade-4f2e5a4917a8" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirationsWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_0fe0e02a-91d5-4607-9833-e00a647c0374" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeituresAndExpirationsWeightedAverageExercisePrice_41f01067-921d-4741-bade-4f2e5a4917a8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsSharesExchangedInPeriodWeightedAverageExercisePrice_62cfb9d0-1fb8-44ac-b214-d7e505a10c20" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsSharesExchangedInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_0fe0e02a-91d5-4607-9833-e00a647c0374" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsSharesExchangedInPeriodWeightedAverageExercisePrice_62cfb9d0-1fb8-44ac-b214-d7e505a10c20" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice_004212c8-6201-44f2-8e55-2901d9ea2a64" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_1d336d83-3e41-4aa1-aee3-d81da7e2e2b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_3a6cd3ca-bdb7-42f5-ac95-6b85b95a164b" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_1d336d83-3e41-4aa1-aee3-d81da7e2e2b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_ffc7b170-03e2-4171-aff2-6c361756bb55" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1d336d83-3e41-4aa1-aee3-d81da7e2e2b0" xlink:to="loc_us-gaap_AwardTypeAxis_ffc7b170-03e2-4171-aff2-6c361756bb55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ffc7b170-03e2-4171-aff2-6c361756bb55_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_ffc7b170-03e2-4171-aff2-6c361756bb55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ffc7b170-03e2-4171-aff2-6c361756bb55_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2b892a4d-13f1-49bb-9b6b-26c64f308156" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_ffc7b170-03e2-4171-aff2-6c361756bb55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2b892a4d-13f1-49bb-9b6b-26c64f308156" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableSharesMember_14ff29f0-66dc-4c47-a625-342c5ab06ed5" xlink:href="cart-20230930.xsd#cart_ExchangeableSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2b892a4d-13f1-49bb-9b6b-26c64f308156" xlink:to="loc_cart_ExchangeableSharesMember_14ff29f0-66dc-4c47-a625-342c5ab06ed5" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/StockholdersEquityDeficitShareBasedPaymentArrangementExpensedandCapitalizedAmountDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#StockholdersEquityDeficitShareBasedPaymentArrangementExpensedandCapitalizedAmountDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/StockholdersEquityDeficitShareBasedPaymentArrangementExpensedandCapitalizedAmountDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_840c8160-e13f-449f-ab29-cdc85440cedd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_840c8160-e13f-449f-ab29-cdc85440cedd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_427a106b-f329-4751-9dde-8bc17dfd7fe4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_427a106b-f329-4751-9dde-8bc17dfd7fe4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_bad2155a-0e71-4113-8e93-074b71be6734" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_bad2155a-0e71-4113-8e93-074b71be6734" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNumberOfShares_d4562f9d-851b-498a-b0c7-c87ba2b105cf" xlink:href="cart-20230930.xsd#cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:to="loc_cart_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNumberOfShares_d4562f9d-851b-498a-b0c7-c87ba2b105cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_0117c81f-5cd2-40bc-9fe3-b35c64257454" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_0117c81f-5cd2-40bc-9fe3-b35c64257454" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_16863839-efe6-4b44-8042-f44ec6430d13" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_16863839-efe6-4b44-8042-f44ec6430d13" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_59abfe26-df29-4d4c-84d1-17aa166610ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_59abfe26-df29-4d4c-84d1-17aa166610ee" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c81e72d2-1dd1-4c0d-a7c7-6b1a612d210c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a5d280f9-e5f1-4a0c-a044-542662302e1b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c81e72d2-1dd1-4c0d-a7c7-6b1a612d210c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_297502f4-329b-42a5-863c-1ecd32731625" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c81e72d2-1dd1-4c0d-a7c7-6b1a612d210c" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_297502f4-329b-42a5-863c-1ecd32731625" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_297502f4-329b-42a5-863c-1ecd32731625_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_297502f4-329b-42a5-863c-1ecd32731625" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_297502f4-329b-42a5-863c-1ecd32731625_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3e46705c-db95-438d-b82d-132d0758f3cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_297502f4-329b-42a5-863c-1ecd32731625" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3e46705c-db95-438d-b82d-132d0758f3cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_a4635507-4e57-4c7a-b8a6-37a840e50a7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3e46705c-db95-438d-b82d-132d0758f3cc" xlink:to="loc_us-gaap_CostOfSalesMember_a4635507-4e57-4c7a-b8a6-37a840e50a7d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_OperationsAndSupportExpenseMember_60e9ec58-52cb-40b6-a0e8-472cdb6803dd" xlink:href="cart-20230930.xsd#cart_OperationsAndSupportExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3e46705c-db95-438d-b82d-132d0758f3cc" xlink:to="loc_cart_OperationsAndSupportExpenseMember_60e9ec58-52cb-40b6-a0e8-472cdb6803dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_6a8f8830-2e21-443b-b530-6427f959e4b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3e46705c-db95-438d-b82d-132d0758f3cc" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_6a8f8830-2e21-443b-b530-6427f959e4b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_6efc7f49-8c3f-4fdd-94a1-27107656bc95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingAndMarketingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3e46705c-db95-438d-b82d-132d0758f3cc" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_6efc7f49-8c3f-4fdd-94a1-27107656bc95" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_80ce381a-0601-4f7a-ad95-35ecd2748d1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3e46705c-db95-438d-b82d-132d0758f3cc" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_80ce381a-0601-4f7a-ad95-35ecd2748d1f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_1bd8b758-2035-4d36-8eed-3186fa318960" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c81e72d2-1dd1-4c0d-a7c7-6b1a612d210c" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_1bd8b758-2035-4d36-8eed-3186fa318960" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_1bd8b758-2035-4d36-8eed-3186fa318960_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_1bd8b758-2035-4d36-8eed-3186fa318960" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_1bd8b758-2035-4d36-8eed-3186fa318960_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_9b886114-b58a-4557-98b9-4f585c9fd9b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_1bd8b758-2035-4d36-8eed-3186fa318960" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_9b886114-b58a-4557-98b9-4f585c9fd9b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_25dd6b34-678d-4555-bd64-42a7bc272a90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IPOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_9b886114-b58a-4557-98b9-4f585c9fd9b1" xlink:to="loc_us-gaap_IPOMember_25dd6b34-678d-4555-bd64-42a7bc272a90" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/NetIncomeLossperShareAttributabletoCommonStockholdersAntidilutiveDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#NetIncomeLossperShareAttributabletoCommonStockholdersAntidilutiveDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/NetIncomeLossperShareAttributabletoCommonStockholdersAntidilutiveDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_c4098cb7-e725-4a0c-b8b1-2caeacb26919" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_5e8759cc-53b6-4f42-aec2-01572324f50b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_c4098cb7-e725-4a0c-b8b1-2caeacb26919" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_5e8759cc-53b6-4f42-aec2-01572324f50b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_ea64b20b-d7ee-4a9d-be1c-ea24b961e77e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_c4098cb7-e725-4a0c-b8b1-2caeacb26919" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_ea64b20b-d7ee-4a9d-be1c-ea24b961e77e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9557ef0e-9265-4173-a0cf-d9490894b9f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_ea64b20b-d7ee-4a9d-be1c-ea24b961e77e" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9557ef0e-9265-4173-a0cf-d9490894b9f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_9557ef0e-9265-4173-a0cf-d9490894b9f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9557ef0e-9265-4173-a0cf-d9490894b9f1" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_9557ef0e-9265-4173-a0cf-d9490894b9f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f37dbf66-2f1a-4f95-aece-f3625838335a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9557ef0e-9265-4173-a0cf-d9490894b9f1" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f37dbf66-2f1a-4f95-aece-f3625838335a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_94ad2397-216b-4585-8022-ccb6506f5dc0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f37dbf66-2f1a-4f95-aece-f3625838335a" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_94ad2397-216b-4585-8022-ccb6506f5dc0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_c3d31f80-cd8d-485a-b379-c36144f67349" xlink:href="cart-20230930.xsd#cart_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f37dbf66-2f1a-4f95-aece-f3625838335a" xlink:to="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_c3d31f80-cd8d-485a-b379-c36144f67349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_df2529b4-0838-402a-a5ad-344c3c6b92fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f37dbf66-2f1a-4f95-aece-f3625838335a" xlink:to="loc_us-gaap_EmployeeStockOptionMember_df2529b4-0838-402a-a5ad-344c3c6b92fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_6c3d526d-9fa6-448c-93dc-fce489fce9aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f37dbf66-2f1a-4f95-aece-f3625838335a" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_6c3d526d-9fa6-448c-93dc-fce489fce9aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_805cc3e2-f4ed-428f-95d7-5eae6da9a3a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f37dbf66-2f1a-4f95-aece-f3625838335a" xlink:to="loc_us-gaap_RestrictedStockMember_805cc3e2-f4ed-428f-95d7-5eae6da9a3a1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_d1c3e579-4937-46fc-9a0e-a0a7814d29cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f37dbf66-2f1a-4f95-aece-f3625838335a" xlink:to="loc_us-gaap_WarrantMember_d1c3e579-4937-46fc-9a0e-a0a7814d29cd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_AntidilutiveSecuritiesConditionAxis_833c1d64-8665-4ef0-a11d-d1a2c3ebe0b0" xlink:href="cart-20230930.xsd#cart_AntidilutiveSecuritiesConditionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_ea64b20b-d7ee-4a9d-be1c-ea24b961e77e" xlink:to="loc_cart_AntidilutiveSecuritiesConditionAxis_833c1d64-8665-4ef0-a11d-d1a2c3ebe0b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_AntidilutiveSecuritiesConditionDomain_833c1d64-8665-4ef0-a11d-d1a2c3ebe0b0_default" xlink:href="cart-20230930.xsd#cart_AntidilutiveSecuritiesConditionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cart_AntidilutiveSecuritiesConditionAxis_833c1d64-8665-4ef0-a11d-d1a2c3ebe0b0" xlink:to="loc_cart_AntidilutiveSecuritiesConditionDomain_833c1d64-8665-4ef0-a11d-d1a2c3ebe0b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_AntidilutiveSecuritiesConditionDomain_393d3a40-3377-45a5-a2f4-950015774579" xlink:href="cart-20230930.xsd#cart_AntidilutiveSecuritiesConditionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cart_AntidilutiveSecuritiesConditionAxis_833c1d64-8665-4ef0-a11d-d1a2c3ebe0b0" xlink:to="loc_cart_AntidilutiveSecuritiesConditionDomain_393d3a40-3377-45a5-a2f4-950015774579" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_PerformanceAndOrMarketBasedConditionsMember_eefa9f48-2e6a-41a4-98d6-283d5d54af42" xlink:href="cart-20230930.xsd#cart_PerformanceAndOrMarketBasedConditionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cart_AntidilutiveSecuritiesConditionDomain_393d3a40-3377-45a5-a2f4-950015774579" xlink:to="loc_cart_PerformanceAndOrMarketBasedConditionsMember_eefa9f48-2e6a-41a4-98d6-283d5d54af42" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_2630cfc1-60d0-4b72-a749-7c08ab964f8a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_ba92f15c-296e-43e2-afab-20a432f71fd9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_2630cfc1-60d0-4b72-a749-7c08ab964f8a" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_ba92f15c-296e-43e2-afab-20a432f71fd9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_5ee197e4-78d1-456d-b9c1-c99f3c4e7e76" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_2630cfc1-60d0-4b72-a749-7c08ab964f8a" xlink:to="loc_us-gaap_OperatingExpenses_5ee197e4-78d1-456d-b9c1-c99f3c4e7e76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_f84853cb-4c9e-4bbf-8c8b-edf2010afac7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_2630cfc1-60d0-4b72-a749-7c08ab964f8a" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_f84853cb-4c9e-4bbf-8c8b-edf2010afac7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_32381926-62cb-4096-aac0-0a746af03718" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_2630cfc1-60d0-4b72-a749-7c08ab964f8a" xlink:to="loc_us-gaap_AccountsPayableCurrent_32381926-62cb-4096-aac0-0a746af03718" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_037a76fa-3812-49ca-a7ec-0a4ca5f216da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_2630cfc1-60d0-4b72-a749-7c08ab964f8a" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_037a76fa-3812-49ca-a7ec-0a4ca5f216da" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_acfdc808-5714-4775-ba44-3b97577e3b91" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_037a76fa-3812-49ca-a7ec-0a4ca5f216da" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_acfdc808-5714-4775-ba44-3b97577e3b91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_acfdc808-5714-4775-ba44-3b97577e3b91_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_acfdc808-5714-4775-ba44-3b97577e3b91" xlink:to="loc_us-gaap_RelatedPartyDomain_acfdc808-5714-4775-ba44-3b97577e3b91_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_f687113f-e80e-4794-9a61-0883075f3a3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_acfdc808-5714-4775-ba44-3b97577e3b91" xlink:to="loc_us-gaap_RelatedPartyDomain_f687113f-e80e-4794-9a61-0883075f3a3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_c912ec6b-b922-49b9-af9e-003866785869" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_f687113f-e80e-4794-9a61-0883075f3a3f" xlink:to="loc_us-gaap_RelatedPartyMember_c912ec6b-b922-49b9-af9e-003866785869" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.instacart.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="cart-20230930.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.instacart.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_6818e720-a79e-4151-84b6-fbe0fa27ae83" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_c1d66122-f2c3-4b37-b446-54dae4f8b969" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_6818e720-a79e-4151-84b6-fbe0fa27ae83" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_c1d66122-f2c3-4b37-b446-54dae4f8b969" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_244f6572-56a8-4b67-a590-3c41dde12243" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_6818e720-a79e-4151-84b6-fbe0fa27ae83" xlink:to="loc_us-gaap_SubsequentEventTable_244f6572-56a8-4b67-a590-3c41dde12243" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_668970aa-3fec-4a14-9411-9a15256b21e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_244f6572-56a8-4b67-a590-3c41dde12243" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_668970aa-3fec-4a14-9411-9a15256b21e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_668970aa-3fec-4a14-9411-9a15256b21e6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_668970aa-3fec-4a14-9411-9a15256b21e6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_668970aa-3fec-4a14-9411-9a15256b21e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_93ff9066-4359-48b1-9d56-35ef48b6e632" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_668970aa-3fec-4a14-9411-9a15256b21e6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_93ff9066-4359-48b1-9d56-35ef48b6e632" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_20106e52-a1e1-42fd-8517-91671bd761f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_93ff9066-4359-48b1-9d56-35ef48b6e632" xlink:to="loc_us-gaap_SubsequentEventMember_20106e52-a1e1-42fd-8517-91671bd761f1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_bee094a1-d602-4c95-9a11-c52b05917edc" xlink:href="cart-20230930.xsd#cart_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_cart_SeriesARedeemableConvertiblePreferredStockMember_bee094a1-d602-4c95-9a11-c52b05917edc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_WarrantMember" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableSharesOutstandingMember_247e9677-592d-4657-9f6c-9cb0e6d11e6c" xlink:href="cart-20230930.xsd#cart_ExchangeableSharesOutstandingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_cart_ExchangeableSharesOutstandingMember_247e9677-592d-4657-9f6c-9cb0e6d11e6c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_SharesAvailableForFutureGrantMember_cde519a9-bce1-4f06-adac-f16667e3e6b6" xlink:href="cart-20230930.xsd#cart_SharesAvailableForFutureGrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_cart_SharesAvailableForFutureGrantMember_cde519a9-bce1-4f06-adac-f16667e3e6b6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_EmployeeStockMember" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockMember" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_cart_ExchangeableSharesMember_20d76a86-bd17-4935-8222-13106a7a8bcc" xlink:href="cart-20230930.xsd#cart_ExchangeableSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_cart_ExchangeableSharesMember_20d76a86-bd17-4935-8222-13106a7a8bcc" xlink:type="arc" order="12"/>
  </link:definitionLink>
</link:linkbase>
