The "Lone Survivor" actor will be joined by Chris O’Dowd ("Bridesmaids"), who is set to play journalist David Walsh. The film is based on Walsh's book "Seven Deadly Sins: My Pursuit of Lance Armstrong."
The casting news was rumored earlier this year, but it's now officially confirmed, according to Deadline.
Guillaume Canet ("Tell No One") and Jesse Plemons (Todd on "Breaking Bad") will also star in the film.
John Hodge ("Trainspotting," "Trance") wrote the screenplay, while Tim Bevan and Eric Fellner will produce for Working Title, along with Tracey Seaward.
The as-yet-untitled Studio Canal film is gearing up for a quick October 18 start date.
Meanwhile, Warner Bros. is developing a separate Armstrong biopic called "Red Blooded American." Bradley Cooper is set to ride as Armstrong for director Jay Roach ("Game Change," "Austin Powers"), who stepped in for J.J. Abrams.
The race is on.