TSM: Mii Yuh-Jier reported employee-plan purchases

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

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-08-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001046179</issuerCik>
        <issuerName>TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD</issuerName>
        <issuerTradingSymbol>TSM</issuerTradingSymbol>
        <issuerForeignTradingSymbol>2330.TW</issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002113729</rptOwnerCik>
            <rptOwnerName>Mii Yuh-Jier</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>NO. 8, LI-HSIN ROAD 6</rptOwnerStreet1>
            <rptOwnerStreet2>HSINCHU SCIENCE PARK</rptOwnerStreet2>
            <rptOwnerCity>HSINCHU</rptOwnerCity>
            <rptOwnerNonUSStateTerritory>TAIWAN</rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>F5</rptOwnerCountry>
            <rptOwnerZipCode>300096</rptOwnerZipCode>
            <rptOwnerStateDescription>TAIWAN</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP and Co-COO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares (2330.TW)</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1254057</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>American Depositary Shares (TSM)</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares (2330.TW)</value>
            </securityTitle>
            <transactionDate>
                <value>2026-08-07</value>
                <footnoteId id="F2"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>72</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>73.31</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8099</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By ESPP Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares (2330.TW)</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>63345</value>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By LTI Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Equity Linked Notes</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
                <footnoteId id="F7"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F6"/>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-03-04</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>American Depositary Shares (TSM)</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>703</value>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>150000</value>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each American Depositary Share represents five (5) Common Shares.</footnote>
        <footnote id="F2">Common Shares purchased by the administrator of the issuer's Employee Stock Purchase Plan (&quot;ESPP&quot;) on behalf of the filer pursuant to terms predetermined by the issuer.</footnote>
        <footnote id="F3">The price was translated from the average purchase price of NT$2,367.1117 in New Taiwan dollars, at the rate of NT$32.288 to US$1.</footnote>
        <footnote id="F4">Common Shares purchased and held under the issuer's Employee Stock Purchase Plan (&quot;ESPP&quot;).</footnote>
        <footnote id="F5">Represents Common Shares purchased by a trust with cash received under the issuer's Long-Term Incentive (&quot;LTI&quot;) Bonus Plan, over which the filer has obtained investment control.</footnote>
        <footnote id="F6">The Equity Linked Notes are issued by UBS AG that reference a basket of equity securities that includes the issuer's American Depositary Shares. The principal amount of the notes is US$150,000. The notes are exercisable and expire on March 4, 2027 (the &quot;Exercisable Date&quot;). Under the terms of the notes, if the notes are not redeemed early and the closing price of the worst-performing basket component is below its strike price on the Exercisable Date, the notes may be settled by delivery of shares or American Depositary Shares of that worst-performing basket component plus cash in lieu of any fractional share. The strike price for each basket component equals 55% of its initial reference level. If the issuer's American Depositary Shares are determined to be the worst-performing basket component, settlement may result in delivery of up to 703 American Depositary Shares of the issuer at a strike price of 213.2515 per American Depositary Share. [Continued in footnote 7]</footnote>
        <footnote id="F7">[Continued from footnote 6] In addition, the notes may be redeemed for cash, (i) if, during the observation period prior to the Exercisable Date, the closing price of each basket component has reached its initial reference level at least once, or (ii) if the notes are not redeemed early and the closing price of the worst-performing basket component is at or above its strike price on the Exercisable Date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jen-Chau Huang, as attorney-in-fact</signatureName>
        <signatureDate>2026-08-10</signatureDate>
    </ownerSignature>
</ownershipDocument>