Joy Behar, JB Smoove and Heather Morris have also joined the cast, which already includes Ray Romano, Queen Latifah, Denis Leary, Jeremy Renner, Drake, Seann William Scott and Jennifer Lopez.
The follow-up to Ice Age: Dawn of the Dinosaurs will see Scrat accidentally starting a series of events that will allow Sid to reunite with his family.
Simon Pegg, Frost's collaborator since Spaced, voiced the one-eyed weasel Buck in Ice Age 3.
Frost was last seen in the sci-fi film Paul, which he and Pegg have ruled out making a sequel to in the future.
The actor has also announced that he will be collaborating again with Pegg on a new project.
Ice Age: Continental Drift will be released in the UK on July 6, 2012 and in the US on July 13, 2012.
Watch Digital Spy's recent interview with Simon Pegg and Nick Frost below: