Mr Cameron did not appear in clips from the video shown during last night's Let's Dance for Comic Relief and a spokesman for the charity was unable to say what his role included.
In the last months of Mr Blair's premiership in 2007, he appeared alongside Catherine Tate and uttered the comedian's catchphrase "Am I bovvered?"
Mr Brown appeared in a comedy sketch with James Corden and boyband JLS in 2011 - after he was voted out of office in the 2010 general election.
The Prime Minister also appeared in last year's programme when he judged the efforts of Miranda Hart, Ruby Wax and Claudia Winkleman who served him a three-course meal in the MasterChef segment.
- One Direction will perform the track for the first time at the BRITS on February 20.