6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OFFOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of June 2023

Commission File Number: 001-35931

Constellium SE

(Translation of registrant’s name into English)

(Address of principal executive offices)

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

Form 20-F  ☒             Form 40-F  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Yes  ☐            No  ☒

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):

Yes  ☐            No  ☒

INFORMATION CONTAINED IN THIS FORM 6-K REPORT

Constellium SE (the “Company”) discloses voting results for proposals submitted at its Annual General Meeting of Shareholders held on June 8, 2023 (the “AGM”), including the re-appointment of Jean-Marc Germain, Michiel Brandjes and John Ormerod to the Company’s Board of Directors for a period of three years following the AGM. The voting results are posted on the Company’s website and are attached and incorporated herein by reference as Exhibit 99.1.

The information contained in this Form 6-K is incorporated by reference into anyoffering circular or registration statement (or into any prospectus that forms a part thereof) filed by Constellium SE with the Securities and Exchange Commission.

SIGNATURE

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

EX-99.1

Exhibit 99.1

CONSTELLIUM SE 2023 ANNUAL GENERAL MEETING VOTING RESULTS

Total Shares Outstanding: 146,819,884

Total Shares Voted: 125,187,736

Total % of Shares Voted: 85.27%

Exhibit 99.1