Xavier Johnson had 18 points and 12 rebounds for Colorado (14-6, 4-4 Pac-12). Spencer Dinwiddie added 16 points and Andre Roberson 15 for the Buffaloes, winners of three straight.
Colorado improved to 9-1 at home despite turning the ball over 20 times.
Justin Cobbs led California (11-8, 3-4) with 22 points. Allen Crabbe, the Pac-12's leading scorer, had 21 points, but only four at halftime.
The Bears scored just 18 points in the first half, their lowest total of the season, while shooting 21 percent before the break. They improved to 61 percent in the second half and finished at 42 percent.