Griffin was cleared to play after sustaining a concussion on a hit taken in the Redskins' loss to Atlanta. He showed few ill effects from the blow, carrying the ball 13 times -- including a game-clinching 76-yard scoring run with 2:43 remaining in the game.
Last year's Heisman Trophy winner completed 17-of-22 passes for 182 yards as the Redskins (3-3) broke an eight-game home losing skid.
Alfred Morris and Darrel Young each added a TD for Washington.
The Vikings (4-2) saw their three-game winning streak snapped despite a big day from Christian Ponder, who racked up 352 yards and two touchdowns on 35-of-52 passing. He was intercepted twice.
Percy Harvin made 11 catches for 133 yards for the Vikings.