UNITED STATES

SECURITIES AND EXCHANGECOMMISSION

WASHINGTON, DC 20549

FORM 6-K

Report of Foreign PrivateIssuer

Pursuant to Rule 13a-16 or 15d-16 under the

Securities Exchange Act of 1934

For the month of November 2025

Commission File Number: 001-41709

 SEALSQCORP

(Exact Name ofRegistrant as Specified in Charter)

N/A

(Translationof Registrant’s name into English)

Indicate by check mark whether the registrantfiles or will file annual reports under cover of Form 20-F or Form 40-F:

☒ Form20-F         ☐ Form 40-F

On November 18, 2025, SEALSQCorp (the “Company” or “SEAL”) reaffirmed its preliminary unaudited financial metrics for the nine-month periodended September 30, 2025 ("9M 2025") and provided some key product milestones and updates.

9M 2025

Key Product Milestones

Forward-Looking Statements

This Current Report on Form6-K expressly or implicitly contains certain forward-looking statements concerning SEALSQ Corp and its businesses. Forward-looking statementsinclude statements regarding our business strategy, financial performance, results of operations, market data, events or developmentsthat we expect or anticipate will occur in the future, as well as any other statements which are not historical facts. Although we believethat the expectations reflected in such forward-looking statements are reasonable, no assurance can be given that such expectations willprove to have been correct. These statements involve known and unknown risks and are based upon a number of assumptions and estimateswhich are inherently subject to significant uncertainties and contingencies, many of which are beyond our control. Actual results maydiffer materially from those expressed or implied by such forward-looking statements. Important factors that, in our view, could causeactual results to differ materially from those discussed in the forward-looking statements include the timing of the launch of key products,SEALSQ's ability to continue beneficial transactions with material parties, including a limited number of significant customers; marketdemand and semiconductor industry conditions; and the risks discussed in SEALSQ's filings with the SEC. Risks and uncertainties are furtherdescribed in reports filed by SEALSQ with the SEC. SEALSQ Corp is providing this Current Report on Form 6-K as of this date and does notundertake to update any forward-looking statements contained herein as a result of new information, future events or otherwise.

The informationcontained in this Report on Form 6-K is hereby incorporated by reference into the registrationstatement on Form F-3 of the Company (File No. 333-290963), as amended, and the registration statement on Form S-8 of the Company (FileNo. 333-287139), and into the base prospectus and any prospectus supplement outstanding under each of the foregoing registrationstatements, to the extent not superseded by documents or reports subsequently filed or furnished by the Company under the Securities Actof 1933, as amended, or the Securities Exchange Act of 1934.

SIGNATURES

Pursuant to the requirements ofthe Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereuntoduly authorized.