He was awarded the Camera d'Or prize along with Claire Burger and Marie Amachoukeli for directing the film Party Girl at the 2014 Cannes Film Festival.

[2] Most recently, he played Samuel Maleski in Anatomy of a Fall, which premiered at the 76th Cannes Film Festival on 21 May 2023, where it won the Palme d'Or and the Palm Dog Award.

In January 2024, it was reported that Theis had been accused of sexually assaulting a crew member during the production of Je le jure (English: I Swear), his third film as director, in summer 2023.

The crew member alleged that they were too inebriated to consent, while Theis asserted that the encounter was consensual.

It was decided that Theis would continue directing, but remotely (from an adjoining room).