The Gators (19-8, 8-4 Southeastern Conference) converted a season-best 25 of 27 free throws, 93 percent, to earn the edge in a battle of teams on the NCAA Tournament bubble. Chandler Parsons scored 13 points and Walker added 10 for Florida.
Terrance Henry led Ole Miss (17-9, 5-7) with 17 points and Chris Warren had 14 points. The Rebels, who were ranked No. 14 in mid-January, have lost five of their last six contests.
Florida took a 58-56 lead with 58 seconds left on Kenny Boynton's layup after a steal by Alex Tyus. The Gators closed it out on their final three possessions as Walker converted six free throws.
Terrico White missed a potential game-tying 3-point shot at the buzzer.