Utah (24-7) had a few offensive problems in the first half, but found a rhythm in the second.
The third-seeded Utes hit 14 of 28 shots in the second half and were 12 of 19 from 3-point range overall to earn a spot in Friday's semifinals against second-seeded Oregon.
Utah also turned up the defensive pressure in the final 20 minutes, holding the Cardinal to 6 of 24 shooting. Jakob Poeltl added 16 points for the Utes.
Stanford (19-13) pulled off an upset in the opening round, but faded against the fresher Utes in the second half.