Cooper is best known for his Academy Award-nominated performance in the film "Silver Linings Playbook" and the "Hangover" comedy trilogy.
"Guardians" will also feature voice performances by Chris Pratt, Zoe Saldana and Dave Bautista.
Directed by James Gunn, the movie opens Aug. 1, 2014.
Aaron Carter is still in love with Hilary Duff
Boston schools pull out free condoms over wrapping complaints