The 29-year-old heartthrob has ditched the curly locks he sported playing Sean Parker in The Social Network in favour of a buzz cut.
And Justin wasn't the only one with a new hairdo. Also spotted on the set was a red-headed Amanda Seyfried, who plays his girlfriend.
Justin was pictured carrying a semi-automatic pistol in a scene where he steals a limousine.
In the movie titled Now, Timberlake plays Olivia Wilde's son, in a world where everyone stops aging at 25 and has to buy time to live.
The film, which was previously called I'm Mortal, is due to hit theatres next year.