Derrious Gilmore added 15 points and Josh Adams had 12 for the Cowboys (17-7, 3-7 Mountain West), who snapped a five-game conference losing streak.
Deonte Burton scored 13 while Malik Story had 11 and Kevin Panzer 10 for Nevada (12-12, 3-7).
Riley Grabau and Gilmore each drained 3-pointers to start the second half, which put the Cowboys up 35-19. Washington’s long jumper pushed the margin to 43-25 with 14:52 remaining and his dunk on a fast break made it 65-42, the widest margin, with 3:33 left.
Nevada had drawn within 47-36 after Burton stole the ball and made a floater. But Adams sparked a 9-0 spurt with two fast-break layup attempts that resulted in four free throws and he also sank a 3 to give Wyoming a 56-36 advantage.