Lespert made his film debut in 1995, in Laurent Cantet's film Jeux de plage, opposite his father. His first major role came in 1999, in Jacques Maillot's film Nos vies heureuses. The following year, he appeared in another Laurent Cantet film Ressources humaines, which earned him a César Award for Most Promising Actor in 2001.
He directed his first film in 2007, 24 mesures, featuring Benoît Magimel and Sami Bouajila. His second feature as Director, Des vents contraires, also featuring Magimel alongside Audrey Tautou and Isabelle Carré, came out in 2011.
