The deal reportedly is worth $2.1 million.
The 24-year-old had 16 goals and 14 assists in 64 games -- all career highs -- last season. He was a plus-9 and had four game-winning goals.
In 120 career games -- all with Washington -- he has 27 goals, 26 assists and is a plus-10.
Perreault was selected by the Capitals in the sixth round (No. 177) of the 2006 NHL Draft. He won back-to-back Calder Cup championships with Hershey of the American Hockey League in 2009 and 2010.