Flat Lick is an unincorporated community and census-designated place (CDP) in Knox County, Kentucky, United States. As of the 2020 census, Flat Lick had a population of 850.
The oldest community in the county, Flat Lick was settled by Europeans before 1784 and named for a salty rock which attracted wild animals.
Flat Lick is in eastern Knox County, northeast of the Cumberland River. U.S. Route 25E forms the western edge of the CDP; the highway leads northwest to Barbourville, the county seat, and southeast to Pineville.
According to the U.S. Census Bureau, the Flat Lick CDP has an area of , of which , or 0.05%, are water.