Williams, a running back who entered the game as the Wildcats' leader in all-purpose yards, stayed down for a couple minutes after being tackled by LSU's D.J. Welter and Deion Jones with 10:30 to go in the third quarter.
He appeared wobbly when he was finally helped to his feet and walked off the field gingerly with each arm around trainers' shoulders.
The Wildcats were trailing 34-3 at the time.
A Kentucky spokesman says Williams has been removed from the game to be evaluated by medical staff and it was unclear whether he'd return to the game.