Exhibit 32.1

Certification pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (18 U.S.C. 1350)

In connection with the quarterly report on Form 10-Q of Century Aluminum Company (the “Company”) for the quarter ended March 31, 2024, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), Jesse E. Gary, as President and Chief Executive Officer of the Company, hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of his knowledge:

1.This Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2.The information contained in this Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

	/s/ JESSE E. GARY
By:	Jesse E. Gary
Title:	President and Chief Executive Officer (Principal Executive Officer)
Date:	May 1, 2024

A signed original of this written statement required by Section 906 has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.