<?xml version="1.0"?>
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    <schemaVersion>X0708</schemaVersion>

    <submissionType>D</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0002043521</cik>
        <entityName>CrossBridge Bio, Inc.</entityName>
        <issuerAddress>
            <street1>2450 HOLCOMBE BLVD, SUITE X</street1>
            <city>HOUSTON</city>
            <stateOrCountry>TX</stateOrCountry>
            <stateOrCountryDescription>TEXAS</stateOrCountryDescription>
            <zipCode>77021</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>(346) 547-5202</issuerPhoneNumber>
        <jurisdictionOfInc>UNITED STATES</jurisdictionOfInc>
        <issuerPreviousNameList>
            <value>None</value>
        </issuerPreviousNameList>
        <edgarPreviousNameList>
            <value>None</value>
        </edgarPreviousNameList>
        <entityType>Corporation</entityType>
        <yearOfInc>
            <withinFiveYears>true</withinFiveYears>
            <value>2023</value>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Michael</firstName>
                <lastName>Torres</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o CrossBridge Bio, Inc.</street1>
                <street2>2450 Holcombe Blvd, Suite X</street2>
                <city>Houston</city>
                <stateOrCountry>TX</stateOrCountry>
                <stateOrCountryDescription>TEXAS</stateOrCountryDescription>
                <zipCode>77021</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Director</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Kyoji</firstName>
                <lastName>Tsuchikama</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o CrossBridge Bio, Inc.</street1>
                <street2>2450 Holcombe Blvd, Suite X</street2>
                <city>Houston</city>
                <stateOrCountry>TX</stateOrCountry>
                <stateOrCountryDescription>TEXAS</stateOrCountryDescription>
                <zipCode>77021</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Director</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Patrick</firstName>
                <middleName>James</middleName>
                <lastName>Crutcher</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o CrossBridge Bio, Inc.</street1>
                <street2>2450 Holcombe Blvd, Suite X</street2>
                <city>Houston</city>
                <stateOrCountry>TX</stateOrCountry>
                <stateOrCountryDescription>TEXAS</stateOrCountryDescription>
                <zipCode>77021</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>William</firstName>
                <middleName>F.</middleName>
                <lastName>McKeon</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o CrossBridge Bio, Inc.</street1>
                <street2>2450 Holcombe Blvd, Suite X</street2>
                <city>Houston</city>
                <stateOrCountry>TX</stateOrCountry>
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                <zipCode>77021</zipCode>
            </relatedPersonAddress>
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            <relationshipClarification></relationshipClarification>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Damir</firstName>
                <lastName>Illich</lastName>
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            <relatedPersonAddress>
                <street1>c/o CrossBridge Bio, Inc.</street1>
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                <zipCode>77021</zipCode>
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            <relatedPersonRelationshipList>
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            <relationshipClarification></relationshipClarification>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Zhiqiang</firstName>
                <lastName>An</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o CrossBridge Bio, Inc.</street1>
                <street2>2450 Holcombe Blvd, Suite X</street2>
                <city>Houston</city>
                <stateOrCountry>TX</stateOrCountry>
                <stateOrCountryDescription>TEXAS</stateOrCountryDescription>
                <zipCode>77021</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
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            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Biotechnology</industryGroupType>
        </industryGroup>
        <issuerSize>
            <revenueRange>Decline to Disclose</revenueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06b</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>false</isAmendment>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2024-10-29</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>false</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isEquityType>true</isEquityType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>0</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>17019978</totalOfferingAmount>
            <totalAmountSold>10818821</totalAmountSold>
            <totalRemaining>6201157</totalRemaining>
            <clarificationOfResponse></clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>23</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
            </findersFees>
            <clarificationOfResponse></clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
            </grossProceedsUsed>
            <clarificationOfResponse></clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>CrossBridge Bio, Inc.</issuerName>
                <signatureName>/s/ Michael Torres</signatureName>
                <nameOfSigner>Michael Torres</nameOfSigner>
                <signatureTitle>Chief Executive Officer</signatureTitle>
                <signatureDate>2024-11-04</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
