Nyassi was selected twice as a substitute on the bench and did not feature for the MLS side this season, according to soccerway.
He made eleven appearances last season.
A club statement on revolutionsoccer.net announced: “We want to wish Sainey all the best as he moves into the next stage of his career,” General Manager Michael Burns said.
“Sainey was always a professional in his time with us and we wish him well.”
Nyassi, 24, made 104 regular-season appearances for the Revolution, including 75 starts since signing with the club as a then youth international player on August 31, 2007, following the FIFA Under-20 World Cup in Canada.
The Gambia international scored eight goals and added four assists in regular-season action with the Revs. He also made four postseason starts in his career.
Nyassi has four caps with The Gambia National Team.
Sainey and Ken Abdoulie Mansally were both signed by the MLS outfit from The Gambia and have been regular until when Mansally was released by the side earlier.
He now plays for MLS outfit Real Salt Lake.
New England Revolution have been rated 14th in the goal.com MLS power rankings with Gambia’s midfielder yet to play for the set for far this season.
The New England Revolution won 2-0 on Saturday away against the Houston Dynamo.They will meet Toronto next Saturday.