The Commanders snapped a two-game slide after taking down the Patriots 20-17 at Gillette Stadium in Foxboro.
Sam Howell completed 29 of his 45 pass attempts for 325 yards, a touchdown and an interception.
Brian Robinson Jr. carried the ball 18 times for 63 yards including a nine-yard TD run.
Jartavius Martin's key interception in the final minute clinched the victory for Washington.
The Commanders are now third in the NFC East at 4-and-5 and will visit the Seattle Seahawks in Week 10.
Mac Jones completed 24 of 44 passes for 220 yards, one touchdown and a pick.
Rhamondre Stevenson carried the ball nine times for 87 yards including a 64-yard run for a score.
New England is now last in the AFC East at 2-and-7 and will face the Indianapolis Colts in Week 10 in Germany.
(Photo by Adam Glanzman/Getty Images)