Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2024	Nov. 07, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-41925
Entity Registrant Name	CG Oncology, Inc.
Entity Central Index Key	0001991792
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	37-1611499
Entity Address, Address Line One	400 Spectrum Center Drive
Entity Address, Address Line Two	Suite 2040
Entity Address, City or Town	Irvine
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92618
City Area Code	949
Local Phone Number	409-3700
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	CGON
Security Exchange Name	NASDAQ
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		67,629,675