The director told Piers Morgan that "there was no other consideration" for the main roles in The Conspirator. The film deals with a woman charged with conspiracy following the assassination of Abraham Lincoln.
Redford said: "I wanted James right from the get-go, there was no other consideration. I knew he was a good actor, had a lot of wonderful energy, but I was amazed at how smart he was about the script and how much he already knew."
He added: "I wanted her [Wright]. I wanted James and Robin. On my end, it was a done deal. I just hoped she'd do it."
The film is released to US cinemas on April 15.
James McAvoy previously revealed that he ignored advice from Redford about his accent.
Watch the trailer for The Conspirator below: