The win snapped a four-game losing streak for Utah (3-5, 1-4 Pac-12) and kept alive hopes of being bowl-eligible for the 10th straight year.
Reggie Topps' 17-yard fumble return for a touchdown gave Utah a 14-3 lead with 2:13 left in the first quarter. The Utes led 28-6 at halftime after a 5-yard TD run by freshman quarterback Travis Wilson.
In his third start, Wilson completed 16 of 24 passes for 156 yards.
Utah intercepted Zach Maynard once and sacked him four times.
Standout receiver Keenan Allen became Cal's all-time receptions leader with 205 catches but didn't get on track until the game was well in hand.
It was the worst loss of the year for the Golden Bears (3-6, 2-4).
Dunn's second career 100-yard kickoff return came after a first-quarter Cal field goal and ignited a ''blackout'' crowd of 45,017. He brought the kick out of the end zone, cut left, then took a step back to the middle before waiting for his blockers, who escorted him unscathed into the other end zone.
His second 100-yard return of the game came on the opening play of the fourth quarter. He took the kickoff up the middle, cut sharply left, then right, evaded a tackle by Steve Williams at the Cal 12-yard line and cut back left again for the score that put Utah up 49-13.
Cal outgained Utah 441-344, but turnovers and penalties hurt the Bears, who scored a pair of late touchdowns after being kept out of the end zone for seven straight quarters.
Utah's defense, which held Oregon State to 228 yards in a road loss last week, allowed Cal to average 10 yards on its first four plays. Defensive end Joe Kruger then made back-to-back plays, stuffing Utah native Isi Sofele on second-and-3 and recording a quarterback hurry to force Cal to settle for a 49-yard Vincenzo D'Amato field goal.
D'Amato added a 38-yarder, his ninth straight, in the second quarter. Otherwise, it was all Utah.
Wilson escaped a sack and ran for 13 yards on third-and-8 to set up Utah's third score.
Utah's fourth score came after Ryan Lacy intercepted a tipped pass with 6:33 left in the second quarter.
Wilson had the big play on the scoring drive, a third-and-17 pass to Kenneth Scott for 24 yards to the Cal 25. Running back John White also broke a tackle on third-and-5.
White finished with 105 yards on 22 carries, with two touchdowns - doubling his season total.
Cal finished with 153 yards rushing, but a huge chunk came on Brendan Bigelow's 57-yard TD on the final play of the third quarter, when the Bears trailed 42-6.
Maynard finished 20 of 32 for 288 yards with two TDs and an interception.
Allen, meanwhile, needed just three catches to become Cal's all-time receptions leader, but he didn't catch his first until 10:52 remained in the third quarter. Five plays later, Lacy made a play against Allen to break up what would have been a 29-yard TD reception.
Allen tied the all-time mark of 202 catches with 4:26 left in the third on a 15-yard reception, but Maynard fumbled the ball away on the next play on a hit by Trevor Reilly. He broke the record on an 11-yard catch with 12:43 remaining, and added a 23-yard TD reception with 12:17 left to play.
A year ago, a 24-point loss to Cal lighted a fire under the Utes, who went on to finish 5-1, including a Sun Bowl victory.
They're hoping a win will do the same, with four games remaining.
Cal has to win out over Washington, Oregon and Oregon State just to be bowl eligible.