James Ennis III missed a potential tying 3-pointer at the buzzer for Memphis.
The Wizards are just 4-13 on the road but now 18-6 at home, where they've compiled their longest winning streak since a 15-game run in the 1988-89 season.
Washington never trailed and led by as many as 19 points in the first half, then held on after a 10-0 run by Memphis made it a two-point game with 2 1/2 minutes left. That's when Wall took over, scoring on consecutive drives.