Florida survived a mistake at the end of regulation to run its record to 6-2. The Gators have lost this year to Ohio State and Syracuse, the second and third-ranked teams in the country.
Patric Young led Florida with a career-best 25 points, hitting 12-of-15 shots from the field. Walker scored 14, although he was just 3-of-17.
Walker hit two free throws with 8 seconds to go in the second half, giving the Gators a three-point lead.
Solomon Hill then took an inbounds pass well behind the 3-point arc and went into a shooting motion. Florida's Casey Prather attempted to block the shot, but hit Hill's arm and a foul was called.
Prather made all three foul shots to tie the game with 3.9 seconds left.
Florida then held Arizona to two field goals in the overtime while making eight foul shots to pull away.
Arizona (6-3) got 23 points from Jesse Perry, but the Wildcats committed 18 turnovers.
Selena Gomez drops F-bomb, walks off stage during Jingle Ball performance
Wisconsin business offering 'therapeutic cuddling' forced to close