Cover - USD ($)	12 Months Ended
	Dec. 31, 2024	Feb. 28, 2025	Jun. 30, 2024
Cover [Abstract]
Document Type	10-K
Document Quarterly Report	true
Document Period End Date	Dec. 31, 2024
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	814-01620
Entity Registrant Name	KKR FS Income Trust
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	88-0591692
Entity Address, Address Line One	201 Rouse Boulevard
Entity Address, City or Town	Philadelphia
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19112
City Area Code	215
Local Phone Number	495-1150
Title of 12(g) Security	Common Shares of Beneficial Interest, par value $0.01 per share
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		31,393,621
Documents Incorporated by Reference	None
Entity Central Index Key	0001930679
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY