Washington has been dealing with injuries at the running back position and was looking to add depth.
Peterson, now on his fourth team, has only 601 rushing yards and two touchdowns since rushing for over 1,400 yards and 11 touchdowns in 2015 with the Vikings.
After putting the four-time All-Pro through a tryout on Monday, the Washington Redskins have signed Peterson, NFL Network Insider Ian Rapoport and NFL Network's Mike Garafolo reported, via a source informed of the situation.
Adrian Peterson is getting another shot to return to the NFL.
The Redskins lost potential starter Derrius Guice for the season when the second-round pick tore his ACL in the team's preseason opener and backups Samaje Perine and Byron Mashall are both now sidelined with ankle injuries. Samaje Perine along with Byron Marshall were both injured in last week's game against the New York Jets; both will miss some time.
On the roster, Washington has Rob Kelley, Kapri Bibbs and Chris Thompson available at running back. The former 1,000-yard rusher signed a two-year deal with the Saints but was traded to the Cardinals on October 10 and was released at the end of the season. In 2012, Peterson rushed for 2,097 yards - second most in a season, after Eric Dickerson.
Jamaal Charles also met with Washington.
The Redskins are turning over a few stones in search of a healthy running back, and they have uncovered some options. But after just three more games, he suffered a season-ending neck injury that also cast his playing future into doubt. That injury brought an early end to Peterson's 2017 season.
But in Arizona, Peterson showed signs he could still be explosive.
In total, Peterson had 529 yards for two touchdowns. He had two games in which he ran for 134 yards and 159 yards, respectively.
The Redskins open the regular season September 9 at Arizona.