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

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-09-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0002066836</issuerCik>
        <issuerName>Conexeu Sciences Inc.</issuerName>
        <issuerTradingSymbol>CNXU</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002128469</rptOwnerCik>
            <rptOwnerName>Purcell Lynn Sebastian</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>11 TRAFFORD RD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BINGHAMTON</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>13901</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-09-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>X</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>217608</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.3</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2951848</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By OnePointTwo Capital Ventures LLC</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrant</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.3</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-09-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>X</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>217608</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.001</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2026-05-12</value>
            </exerciseDate>
            <expirationDate>
                <value>2029-05-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>217608</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>407392</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By OnePointTwo Capital Ventures LLC</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The 217,608 shares of common stock acquired in Table I and the 217,608 warrants disposed of in Table II represent the exercise on September 4, 2026 of warrants held by OnePointTwo Capital Ventures LLC to purchase 217,608 shares of common stock at an exercise price of $2.30 per share.</footnote>
        <footnote id="F2">The 2,951,848 shares of common stock reported in Table I, Column 5 are held by OnePointTwo Capital Ventures LLC and OnePointTwo Capital Ventures II LLC. OnePointTwo Capital Management LLC serves as manager of OnePointTwo Capital Ventures LLC and OnePointTwo Capital Ventures II LLC. As the managing member of OnePointTwo Capital Management LLC, Lynn Sebastian Purcell has voting and investment power over the securities held by each such entity and may therefore be deemed to beneficially own such securities. Lynn Sebastian Purcell disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any.</footnote>
        <footnote id="F3">The 407,392 warrants reported in Table II, Column 9 are held by OnePointTwo Capital Ventures LLC. OnePointTwo Capital Management LLC serves as manager of OnePointTwo Capital Ventures LLC and OnePointTwo Capital Ventures II LLC. As the managing member of OnePointTwo Capital Management LLC, Lynn Sebastian Purcell has voting and investment power over the securities held by each such entity and may therefore be deemed to beneficially own such securities. Lynn Sebastian Purcell disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Lynn Sebastian Purcell</signatureName>
        <signatureDate>2026-09-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
