Gabe York and Nick Johnson both scored 15 points for the Wildcats (24-2, 11-2 Pac-12).
Rondae Hollis-Jefferson came off the bench to score 13 for Arizona, including six in overtime. Johnson was 4-for-4 from the free-throw line in the extra period, including a pair with 1.9 seconds to play that iced the game for the Cats.
Arizona held a comfortable 35-26 lead at halftime, but was outscored 30-21 in the second half.
Brandon Taylor led Utah (17-9, 6-8) with 13 points. Delon Wright and Dallin Bachynski both scored 12, but the Utes were a mushy 13-for-22 at the free-throw line.