D. J. Seeley added 15 points for the Titans (2-2), who never trailed.
Alec Brown had 20 points and seven rebounds, and Jordan Fouse and Sultan Muhammad added 11 points each for the Phoenix (2-2).
Cal State Fullerton continued its recent hot shooting. A day after making 64.9 percent of their shots in a win against Southern Utah, the Titans were 29 of 53 (54.7 percent) from the floor. They made 10 of 20 3-point attempts.
Green Bay shot just 31 percent (9 of 29) in the first half en route to trailing 48-30 at intermission.
Fouse had nine rebounds for Cal State Fullerton, which outrebounded the Phoenix 41-26.