Menifield's effort helped the Huskies get off to a 3-0 start for the first time since the 2015-16 season.
Washington used a pair of big runs to build an advantage the Wildcats couldn't overcome.
The Huskies pulled away with 10 minutes left in the contest, going on a 16-2 run over six minutes.
The Huskies shook off an uneven start and dominated the final 30 minutes of the game, ending the regular season on a three-game winning streak as the team prepares for postseason play.
The Washington men's basketball team fell to UCLA 77-66 in the Monday night make-up contest. It was a back-and-forth game until the second half when the Bruins (21-6, 13-5) were able to pull away.