Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2025	Aug. 07, 2025
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2025
Document Transition Report	false
Entity File Number	001-41013
Entity Registrant Name	GCT Semiconductor Holding, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	86-2171699
Entity Address, Address Line One	2290 North 1st Street, Suite 201
Entity Address, City or Town	San Jose
Entity Address State Or Province	CA
Entity Address, Postal Zip Code	95131
City Area Code	408
Local Phone Number	434‑6040
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		55,859,904
Entity Central Index Key	0001851961
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q2
Amendment Flag	false
Common Stock
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	GCTS
Security Exchange Name	NYSE
Warrants, each whole warrant exercisable for one share of Common Stock for $11.50 per share
Title of 12(b) Security	Warrants, each whole warrant exercisable for one share of Common Stock for $11.50 per share
Trading Symbol	GCTSW
Security Exchange Name	NYSE