The Twilight actress will play Marylou, the wife of Garrett Hedlund's Dean Moriarty, in director Walter Selles's adaptation of the iconic Beat Generation novel.
"I am very much attached to a movie that has been trying to get made forever," Stewart told USA Today. "Not that this is going to help it, but maybe I can just brag a little bit. I am super excited about it, too. I am about to play Marylou in On The Road. So that's a big deal."
Sam Riley (Control) has also been rumoured to be up for one of the lead roles in the long-in-development project, which will be produced by Francis Ford Coppola.