Ryan Silva added 12 points, all on 3-pointers, for the Aggies (5-8, 1-0 Big West).
Gerard Anderson had 13 points and nine rebounds for the Titans (5-7, 0-1), who lost their seven straight road game.
UC Davis built a 14-point lead early in the second half, but Cal State-Fullerton rallied.
Eric Williams' free throws cut the margin to 64-62 with 32 seconds to play, but the Titans couldn't get any closer. The Aggies made three free throws down the stretch to clinch the win.
Mark Payne's two free throws with 0.8 seconds remaining in the first half completed a 17-6 run and gave the Aggies a 37-26 lead at the break.