According to the Hollywood Reporter, Blanchett, 37, has agreed to star in the upcoming adventure film. The role that the actress will play has not yet been revealed.
Harrison Ford, 64, will return to his title role in the film once more, and the Lucasfilm project will be directed by Steven Spielberg.
Filming is set to begin in June in Los Angeles, before shooting on location at various spots around the world. Indiana Jones 4 should make it to theatres on May 22, 2008.