Freshman tailback Joe McKnight rushed for 89 yards and a touchdown, sophomore Stafon Johnson ran for 73 yards and senior Chauncey Washington gained 66 yards and scored a touchdown.
Booty also erased the memory of last year's game against UCLA when a potential game-winning pass was tipped and intercepted in the final minutes.
Booty completed 21 of 36 passes for 206 yards with a touchdown and an interception. Booty's game-clinching touchdown pass to Fred Davis in the fourth quarter came after Dorrell made what proved to be the game's pivotal decision.
USC had taken a 17-0 second-quarter lead on touchdown runs by McKnight and Washington and a 46-yard field goal by David Buehler. The Bruins pulled to within 10 points when Dominique Johnson made a spectacular one-handed touchdown catch with seven seconds left in the half.
UCLA remained within striking distance despite a third quarter that featured a fumble by Bruins receiver Brandon Breazell, a fumble by McKnight and an interception by USC cornerback Terrell Thomas within 80 seconds.
After Thomas' interception at the Bruins' 43, the Trojans drove toward the end zone and faced a third-and-goal from the two. Johnson was stopped short, and tackle Sam Baker was called for holding.
Rather than declining the penalty and forcing the Trojans into a fourth-down situation, Dorrell opted to take the penalty, later explaining that backing USC up gave the Bruins' defense more space to operate.
On the next play, Booty hit Davis over the middle and the tight end escaped the grasp of linebacker Christian Taylor en route to the end zone and a 24-7 lead.
"We had a great call and we missed a tackle," Dorrell said. "We had everybody covered. We were there to make the play and Christian Taylor didn't make the play. If we make the tackle there, it's fourth and six."
Instead, the game was essentially over.
USC players left the locker room uncertain who their Rose Bowl opponent would be. But they were looking forward to playing in Pasadena for the third year in a row.
"We were all talking about how we're tired of going to the Rose Bowl," Thomas said. "But you know what?