After finishing The Expendables the 62 year old star will step into the role of a lion in the forthcoming animated movie "The Zookeeper".
Sly has signed up to voice the animal role alongside Adam Sandler, Cher, Judd Apatow and Jon Favreau.
The lead roles will be played by 'Seven Pounds' star Rosario Dawson and 'Hitch' funnyman Kevin James.
The film - which will be produced by Adam Sandler's company Happy Madison - will see a group of animals attempt to teach their zookeeper, played by Kevin, how to win his dream woman, Rosario.
Adam will voice the part of a monkey, Jon a bear, Judd an elephant and Cher a giraffe.
Frank Coraci - who is best known for his directorial work on Adam's comedic offerings 'The Wedding Singer' and 'Click' - is in charge of the screenplay by 'Norbit' writers Jay Scherick and David Ronn.
Filming is due to start in Boston in October is scheduled for release in October 2010.