Lou Roy-Lecollinet was born in Saint-Maur-des-Fossés, a suburb of Paris. While still a lycée pupil, and following the advice of her drama teacher, she auditioned for a role in the film My Golden Days, directed by Arnaud Desplechin. In interviews, she has claimed that she became an actress almost by chance. She told one interviewer, "I didn’t want to be an actress. I wanted to direct plays onstage." The film, a prequel to the director's earlier My Sex Life... or How I Got into an Argument (1996), was presented at the 2015 Cannes Film Festival. She was nominated for the César Award for Most Promising Actress for her role in it. She also guest starred in a pc music video for Danny L. Harle in 'Broken Flowers'