The veteran free agent linebacker announced on Twitter on Friday: "Redskins fans your captain is back!"
Fletcher, who turns 37 next month, has been the anchor of Washington's defense for five seasons. He's never missed a game in his NFL career, having played in 224 straight since debuting with the St. Louis Rams in 1998.
The Redskins have said all along that re-signing Fletcher was a priority, and he consistently expressed his desire to return. The deal got done in time for the start of the team's offseason conditioning program on Monday.