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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-10-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000944075</issuerCik>
        <issuerName>SOCKET MOBILE, INC.</issuerName>
        <issuerTradingSymbol>SCKT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001192161</rptOwnerCik>
            <rptOwnerName>BASS CHARLIE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>40675 ENCYCLOPEDIA CIR.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>FREMONT</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Subordinated Convertible Note</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.34</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2025-10-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>373134</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>500000</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>373134</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2823382</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On 10/13/2025, Mr. Kevin Mills transferred a $500,000.00 principal amount of Convertible Note, originally issued on May 26,2023, to Mr. Charlie Bass. The number of underlying shares represents the number of common shares into which the note may be converted.</footnote>
        <footnote id="F2">The Subordinated Convertible note is convertible any time on or prior to May 26, 2026. In addition, after May 26, 2024, the noteholder has the option to receive the prepayment of principal and accrued interest in cash.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Charlie Bass</signatureName>
        <signatureDate>2025-10-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
