Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Aug. 10, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2021
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2021
Entity Registrant Name	Adicet Bio, Inc.
Entity Central Index Key	0001720580
Trading Symbol	ACET
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	001-38359
Entity Tax Identification Number	81-3305277
Entity Address, Address Line One	200 Clarendon Street
Entity Address, Address Line Two	Floor 6
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02116
City Area Code	857
Local Phone Number	315-5528
Entity Common Stock, Shares Outstanding		31,842,263
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE