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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019caede-7f32-74a4-8149-155f9c806c0b,g:91d94fbf-3410-46ab-85d9-15c93a9fdbd5-->
<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.mynycb.com/role/DocumentandEntityInformation_2" xlink:type="simple" xlink:href="nycb-20260424.xsd#DocumentandEntityInformation_2"/>
  <link:definitionLink xlink:role="http://www.mynycb.com/role/DocumentandEntityInformation_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_019caede-7f32-724f-a18d-ca3f68f9cea2" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_DocumentInformationTable_019caede-7f32-724f-a18d-ca3f68f9cea2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019caede-7f32-745b-929e-955ec18bf7ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_019caede-7f32-724f-a18d-ca3f68f9cea2" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019caede-7f32-745b-929e-955ec18bf7ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019caede-7f32-745b-929e-955ec18bf7ff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019caede-7f32-745b-929e-955ec18bf7ff" xlink:to="loc_us-gaap_ClassOfStockDomain_019caede-7f32-745b-929e-955ec18bf7ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019caede-7f32-7252-aa28-8d946144c2ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019caede-7f32-745b-929e-955ec18bf7ff" xlink:to="loc_us-gaap_ClassOfStockDomain_019caede-7f32-7252-aa28-8d946144c2ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019caede-7f32-7318-9606-cd7e7d1048d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019caede-7f32-7252-aa28-8d946144c2ff" xlink:to="loc_us-gaap_CommonStockMember_019caede-7f32-7318-9606-cd7e7d1048d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nycb_BifurcatedOptionNotesUnitSecuritiesMember_019caede-7f32-7c56-bd9b-cb510ba5fd93" xlink:href="nycb-20260424.xsd#nycb_BifurcatedOptionNotesUnitSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019caede-7f32-7252-aa28-8d946144c2ff" xlink:to="loc_nycb_BifurcatedOptionNotesUnitSecuritiesMember_019caede-7f32-7c56-bd9b-cb510ba5fd93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nycb_FixedToFloatingRateSeriesANoncumulativePerpetualPreferredStockMember_019caede-7f32-71e7-bdb9-3b63bad65729" xlink:href="nycb-20260424.xsd#nycb_FixedToFloatingRateSeriesANoncumulativePerpetualPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019caede-7f32-7252-aa28-8d946144c2ff" xlink:to="loc_nycb_FixedToFloatingRateSeriesANoncumulativePerpetualPreferredStockMember_019caede-7f32-71e7-bdb9-3b63bad65729" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019caede-7f32-7d99-9a12-126c7922aed0" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_SecurityExchangeName_019caede-7f32-7d99-9a12-126c7922aed0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019caede-7f32-79a5-a022-7101b74086dd" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_Security12bTitle_019caede-7f32-79a5-a022-7101b74086dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019caede-7f32-7a6e-818a-9a7bd17f7c78" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_TradingSymbol_019caede-7f32-7a6e-818a-9a7bd17f7c78" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019caede-7f32-7022-a0a3-25be9f3285b5" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_DocumentPeriodEndDate_019caede-7f32-7022-a0a3-25be9f3285b5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019caede-7f32-7e99-b007-5ca0ea4f5112" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_DocumentType_019caede-7f32-7e99-b007-5ca0ea4f5112" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019caede-7f32-7114-9bd9-546ed770d8c2" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentType"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019caede-7f32-7fa3-8857-2c23fd6f558f" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_AmendmentFlag_019caede-7f32-7fa3-8857-2c23fd6f558f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019caede-7f32-707f-884d-0f4a9af19d8c" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentPeriodEndDate"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019caede-7f32-7f6c-9d23-0f1d36ca52bf" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityRegistrantName_019caede-7f32-7f6c-9d23-0f1d36ca52bf" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019caede-7f32-75ff-ad60-0b52e41f7abb" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityCentralIndexKey_019caede-7f32-75ff-ad60-0b52e41f7abb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019caede-7f32-7ce6-b0ed-b2bbaa43c1df" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019caede-7f32-7ce6-b0ed-b2bbaa43c1df" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019caede-7f32-721e-bacc-c9aa4ab29b74" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityTaxIdentificationNumber_019caede-7f32-721e-bacc-c9aa4ab29b74" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019caede-7f32-7e6e-91d4-bcdc1af0124d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityAddressCityOrTown_019caede-7f32-7e6e-91d4-bcdc1af0124d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019caede-7f32-7f29-acaf-9e9606082801" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityAddressPostalZipCode_019caede-7f32-7f29-acaf-9e9606082801" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019caede-7f32-7d61-930d-73e36e8d68a4" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_CityAreaCode_019caede-7f32-7d61-930d-73e36e8d68a4" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019caede-7f32-7998-b9dc-32d9da7b75cb" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_LocalPhoneNumber_019caede-7f32-7998-b9dc-32d9da7b75cb" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_019caede-7f32-7fe3-8581-033f11d9aee0" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_WrittenCommunications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_WrittenCommunications_019caede-7f32-7fe3-8581-033f11d9aee0" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_019caede-7f32-7e20-837a-f9900b2f7d11" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_SolicitingMaterial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_SolicitingMaterial_019caede-7f32-7e20-837a-f9900b2f7d11" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_019caede-7f32-7b95-a0e9-34e5f2f4ab34" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_PreCommencementTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_PreCommencementTenderOffer_019caede-7f32-7b95-a0e9-34e5f2f4ab34" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_019caede-7f32-796a-9468-4b14048bf9a9" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_019caede-7f32-796a-9468-4b14048bf9a9" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019caede-7f32-7ac9-8331-9b15cbc750d2" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityEmergingGrowthCompany_019caede-7f32-7ac9-8331-9b15cbc750d2" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019caede-7f32-74af-870f-318156889989" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityFileNumber_019caede-7f32-74af-870f-318156889989" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019caede-7f32-7702-980c-568b625c297f" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityAddressAddressLine1_019caede-7f32-7702-980c-568b625c297f" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019caede-7f32-76b0-9086-8c50298f5aca" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019caede-7f32-78f6-af84-fd6a278f7cf1" xlink:to="loc_dei_EntityAddressStateOrProvince_019caede-7f32-76b0-9086-8c50298f5aca" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019caede-7f32-7683-8d50-26b2431aaa57" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_SecurityExchangeName"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019caede-7f32-7145-a532-aff57fa706cb" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_Security12bTitle"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019caede-7f32-7d92-8ae6-91df16be14d2" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_TradingSymbol"/>
  </link:definitionLink>
</link:linkbase>
