In the film, the 30-year-old actor will play the dynamic, intense, and explosive leader of the Bravo Company squad, Sgt. Dime, reported Deadline.
The adaptation of the Ben Fountain novel centers around 19-year-old private Billy Lynn, who with his mates survived a harrowing Iraq battle that is captured by news cameras.
They are brought home by the US administration for a promotional tour, culminating at the spectacular halftime show of a Thanksgiving Day football game, all while facing an imminent return to the war.
Lee has cast newcomer Joe Alwyn for the title role and Steve Martin has been in talks to star, but it looks like scheduling issues might keep him out of the film.
Hedlund was last seen in the Angelina Jolie-directed 'Unbroken'. His other recent film roles include 'Country Strong', 'Tron Legacy', 'Inside Llewyn Davis', and 'On The Road'. He also co-stars with Oscar Isaac in the William Monahan-directed 'Mojave', which is premiering at the Tribeca Film Festival.