The announcement was made Tuesday by David Nevins, president of entertainment at Showtime Networks Inc.
Season 2 is to debut in 2014.
"'Ray Donovan' is on track to be our biggest Season 1 show ever," Nevins said in a statement.
"Ann Biderman and the extraordinarily talented creative team, coupled with the brilliant ensemble cast led by Liev Schreiber, have produced one of the hottest new dramas of the year. We are proud and excited to pick up another season."