GCT Semiconductor Holding (GCTS) 10-Q 2024 Q3 Quarterly report

EXHIBIT 32.1

CERTIFICATION PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

I, John Schlaefer, Chief Executive Officer of GCT Semiconductor Holding, Inc. (the “Company”), certify that:

1. the Quarterly Report on Form 10-Q of the Company for the three months ended September 30, 2024 as filed with the Securities and Exchange Commission (the “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 the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: November 14, 2024

/s/ John Schlaefer

John Schlaefer

Chief Executive Officer

(Principal Executive Officer)