<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0607</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2026-03-31</periodOfReport>

    <dateOfOriginalSubmission>2026-03-17</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001386716</issuerCik>
        <issuerName>Star Bulk Carriers Corp.</issuerName>
        <issuerTradingSymbol>SBLK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002005037</rptOwnerCik>
            <rptOwnerName>Zagari Raffaele</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O STAR BULK MANAGEMENT INC</rptOwnerStreet1>
            <rptOwnerStreet2>40 AG KONSTANTINOU</rptOwnerStreet2>
            <rptOwnerCity>ATHENS</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>J3</rptOwnerCountry>
            <rptOwnerZipCode>15124</rptOwnerZipCode>
            <rptOwnerStateDescription>GREECE</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common shares, par value $0.01 per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>31500</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Correcting typo in directly owned shares on the original submission (11,750)</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Raffaele Zagari</signatureName>
        <signatureDate>2026-04-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
