Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2023	Jul. 31, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Entity Registrant Name	Bolt Biotherapeutics, Inc.
Entity Central Index Key	0001641281
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		37,950,986
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Title of 12(b) Security	Common Stock, $0.00001 par value
Trading Symbol	BOLT
Security Exchange Name	NASDAQ
Entity File Number	001-39988
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-2804636
Entity Address, Address Line One	900 Chesapeake
Entity Address, Address Line Two	Drive
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94063
City Area Code	650
Local Phone Number	665-9295
Document Quarterly Report	true
Document Transition Report	false