Wall, who scored 15 points in the game, broke an 85-85 tie Golden State's David Lee had forged with his bucket with 1:47 to play.
Bradley Beal led the Wizards with 20 points and seven rebounds.
Stephen Curry led the Warriors with 23 points despite hitting just 8-of-23 shots from the field. Golden State has lost five of their last seven games.
Both teams shot just over 35 percent from the field. The Wizards out-rebounded their hosts 56-47.