Roderick Bobbitt led the defensive effort with eight steals to go with six points and 10 assists. Stefan Jankovic added 15 points and Isaac Fleming scored 10. Hawaii (13-5, 1-1 Big West) tied the steals mark it set against Tennessee Tech in 1988.
Valdes capped a 15-3 run at 64-51 on a jumper with 10:26 left and Hawaii led by double digits the rest of the way.
The Rainbow Warriors led 39-37 at halftime and trailed early in the second but took the lead for good at 45-44 on a pair of Valdes' free throws.