Cunningham is the all-time leading scorer in Major League Soccer history with 134 goals, and Mendoza led the club with 13 goals last season.
Cunningham made 21 appearances last season, just four starts, and scored twice to become the all-time leading scorer in MLS history. Mendoza emerged as a top striker in MLS in his 29 appearances, adding two assists to his goal output.
The Crew also declined options on goalkeeper Alex Riggs and midfielders Kevin Burns, Santiago Prim, Dejan Rusmir and Ben Sippola. Burns played 19 matches in 2011, while Rusmir appeared in 18.
Columbus also exercised contract options on 14 players and extended qualifying offers to midfielders Robbie Rogers and Emmanuel Ekpo, who are out of contract with the club.