Brehaut, who was named starter after Kevin Prince struggled in last week's loss to Texas at the Rose Bowl, completed seven of 11 passes for 146 yards.
Brehaut, who was named starter for the game after Kevin Prince struggled in last week's loss to Texas at the Rose Bowl, completed seven of 11 passes for 146 yards for the Bruins (2-2, 1-0 Pac-12).
The loss spoiled redshirt freshman Sean Mannion's debut as starter for the Beavers, who fall to 0-3 for the first time since 1996. Mannion completed 24 of 40 passes for 287 yards and a touchdown, but he was also intercepted and had a costly fumble for a UCLA score.
After the Bruins scored to make it 27-19 with 6:15 to go, the Beavers drove down field but were stopped at the UCLA 22-yard line when they tried to go for it on fourth-and-eight.
UCLA vacillated between quarterbacks in their first three games, but coach Rick Neuheisel named Brehaut the starter for game after Prince threw three interceptions in the 49-20 loss to the then-No. 23 Longhorns last week.
Because of the Bruins' slow start, Neuheisel was facing increasing questions about his job security at his alma mater.
The Beavers have had their own trouble, a stunning overtime loss at home to Sacramento State in the opener before a 35-0 blanking by Wisconsin. During last week's bye, coach Mike Riley decided to make a change at quarterback, replacing junior Ryan Katz with Mannion.
Rodgers, who has had two surgeries on his left knee, was formally cleared to play by doctors earlier this week. He was greeted by a standing ovation when he started, and had a 31-yard reception on the Beavers' first series.
Oregon State went up 3-0 on Trevor Romaine's 25-yard field goal, but Brehaut answered for UCLA with a 69-yard pass to Josh Smith that put the Bruins in position for his 22-yard touchdown pass to Taylor Embree.
Brehaut ran five yards for another score to put UCLA up 14-3.
Mannion's fumble on the Beavers' own 4-yard line led to Jordan James' touchdown run for UCLA. But Oregon State narrowed it to 21-10 before the half on Jordan Poyer's 85-yard punt return. It was the second-longest such return In Oregon State history. Dwayne Owens had a 97-yard punt return for OSU against UCLA in 1992.
Romaine opened the second half with a 30-yard field goal for the Beavers, and the momentum looked to shift in Oregon State's favor after Andrew Seumalo blocked a UCLA field goal attempt.
Mannion's 45-yard touchdown pass to Jordan Bishop pulled Oregon State within 21-19, but the two-point conversion pass was intercepted.
The Bruins got more breathing room on Anthony Barr's 1-yard scoring dive for the final margin with 6:15 left. Seumalo blocked the extra point, but the Beavers were unsuccessful on their final drive.
Rodgers was ranked sixth in the nation with an average of 176.75 all-purpose yards last season when he was hurt five games into the season at Arizona. The Beavers asked for and received a fifth year of eligibility for him.
He was played sparingly, finishing with five catches for 76 yards.
Halahuni, who had six touchdown catches last season, had surgery this spring on his left shoulder. He had five receptions for 26 yards.
Derrick Coleman had 20 carries for 100 yards for the Bruins.