The Twilight star will play a rookie con artist who teams up with an experienced veteran, played by Ben, and the pair become lovers in new movie Focus.
Kristen told The Huffington Post: "I can confirm that rumour. It's a comedy. I'm really excited about it. We start shooting in April."
It has been claimed Kristen, 22, will have to shoot passionate love scenes with Ben, 40, for the film.
Ben recently said he hoped K- Stew would take the role because she's "terrific".
Kristen also revealed she does not have any other projects in the pipeline, but "would love to find some micro-project before then, because April is kind of a ways away."
Focus will be written and directed by Glenn Ficarra and John Requa, who worked together on Crazy, Stupid, Love.