N-2 - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Apr. 03, 2023	Dec. 31, 2022
Cover [Abstract]
Entity Central Index Key	0001930679
Amendment Flag	false
Securities Act File Number	814-01620
Document Type	10-Q
Entity Registrant Name	KKR FS Income Trust
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
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Financial Highlights [Abstract]
Senior Securities Amount	$ 86,611	$ 94,746
General Description of Registrant [Abstract]
NAV Per Share	$ 29.19	$ 28.84		$ 25.82
Series A Preferred Stock [Member]
Financial Highlights [Abstract]
Preferred Stock Liquidating Preference			$ 1,000