"On behalf of the Montreal Alouettes, I would like to thank both players for their contributions both on the field and in the Montreal community," Alouettes owner Bob Wetenhall said in a statement. "Anwar has been a leader on this team throughout his career and he will always be a member of the Alouettes family."
Stewart, who played his college football at Kentucky, has registered 66 sacks, 10 interceptions and 284 tackles over his CFL career and helped Montreal capture three Grey Cup titles.
He was the CFL's top defensive player in 2004 and a league all-star in 2004 and 2009.
Desriveaux, a native of Laval, Que., spent five seasons with the Alouettes after being drafted by the CFL club in 2006 . The 30-year-old was a member of Grey Cup-winning teams 2009 and 2010.