Company: GCTS
Filing Date: 2025-03-26
Form Type: 424B3
Source: 0000929638-25-001281
Chunk: 211

Company: GCT Semiconductor Holding, Inc.
Filing Date: 2025-03-26
Form: 424B3
Chunk 211
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 record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

| Date: March 25, 2025 |     | By: | /s/ Edmond Cheng        |
|:---------------------|:----|:----|:------------------------|
|                      |     |     | Edmond Cheng            |
|                      |     |     | Chief Financial Officer |

Exhibit 32.1

### CERTIFICATION PURSUANT TO
<div align='center'>18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002</div>

In connection with the Annual Report of GCT Semiconductor Holding, Inc. (the “Company”) on Form 10-K for the period ending December 31, 2024 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that:

(1) 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 result of operations of the Company.

| Date: March 25, 2025 |     | By: | /s/ John Schlaefer      |
|:---------------------|:----|:----|:------------------------|
|                      |     |     | John Schlaefer          |
|                      |     |     | Chief Executive Officer |

Exhibit 32.2

### CERTIFICATION PURSUANT TO
<div align='center'>18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002</div>

In connection with the Annual Report of GCT Semiconductor Holding, Inc. (the “Company”) on Form 10-K for the period ending December 31, 2024 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I certify, pursuant to 18 U.S.C. §