Graham Gano kicked four field goals as the Panthers held on for its second straight win.
Cam Newton completed 21 of 37 passes for 300 yards and tight end Greg Olsen had six catches for 85 yards for Carolina, which scored 10 points in the third quarter to go up by 14.
Graham Gano kicked four field goals as the Panthers held on for its second straight win in front of a crowd of 91,700 at FedEx Field.
Washington dropped to 7-6-1 in the NFL season and the loss leaves them on the outside looking in at the playoffs with two games remaining.
Meanwhile, Carolina (6-8) kept its slim playoff hopes alive.
Redskins quarterback Kirk Cousins passed for 316 yards on 32 of 47 passing with one interception. DeSean Jackson caught seven passes for 111 yards, but Washington was held to just 29 yards rushing.
The Panthers have won five straight against Washington, which fell to 2-16 in Monday night games at FedEx Field.
Redskins cornerback Josh Norman played his first game against his former team, who let the all-star leave after four seasons. Norman almost had an interception when he broke up a third-quarter Newton pass in the end zone.