The Bruins jumped to a 16-4 lead and then turned back a California comeback with a 15-2 run late in the first half.
California, which lost six of its last seven games, finished the season at 16-15. The Golden Bears were led by Ryan Anderson with 15 points.
Collison made five of seven shots from three-point range and UCLA hit 53 percent of its field goal attempts.
UCLA is expected to receive a No. 1 seed when the NCAA Tournament bracket is announced Sunday.