Pitt had a scene-stealing role in the 1993 movie "True Romance," which Tarantino wrote and Tony Scott directed.
Tarantino's fellow filmmaker Eli Roth has signed on to play a supporting role as a soldier in the movie.
Producers told Variety.com casting should be finished this month.
Writer-director Tarantino is expected to start shooting "Basterds" Oct. 13 in Germany.
Pitt, his girlfriend Angelina Jolie and their six children are living in France.