The 54-year-old 'Dark Knight Rises' actor has become the latest star to sign on to Matt Reeves' sci-fi sequel, set 15 years after the events of the James Franco-fronted 2011 film, 'Rise of the Planet of the Apes', reported Deadline.
Oldman will play Dreyfus, a man who leads a human colony struggling to survive in San Francisco after society has been eliminated by the ape-borne flu seen spreading at the end of the last movie.
He joins returning cast member Andy Serkis, who is reprising his role as CGI-enhanced intelligent ape Ceasar, the leader of the monkey rebellion.
Franco has denied being involved with 'Dawn of the Planet of the Apes'.
His cameo role was scrapped after Rupert Wyatt - who directed 'Rise of the Planet of the Apes' - pulled out of directing the film.
'Dawn Of The Planet Of The Apes' begins filming this month in New Orleans for a May 2014 release.