At the age of 18, Guillaume Gallienne decided to simultaneously study theatre and History. Having trained at the Cours Florent for four years, he joined the Conservatoire national supérieur d’art dramatique (Paris Conservatory) following courses taught by Daniel Mesguich, Dominique Valadié and Stéphane Braunschweig. When he was an intern at the Théâtre du Vieux-Colombier in 1996, Daniel Mesguich entrusted him with the role of Arcas in Racine’s Mithridate. Claude Mathieu was playing Queen Monime in the same play and inspired him to join the House of Molière. Guillaume Gallienne replaced an injured actorwhile working as an understudy in Shakespeare’s The Tempest directed by Mr Mesguich at the Comédie-Française. That same evening in July 1998, he was named pensionnaire in order to play in Brecht’s Mother Courage and Her Children under the direction of Jorge Lavelli. In 2005, he became the 513th sociétaire of the Comédie-Française. As part of the company, he has performed in a number of plays including the following: Molière’s Les Femmes savantes directed by Simon Eine; Feydeau’s Un fil à la patte under the direction of Jérôme Deschamps (for which he won the Molière Award for best supporting role); Chekhov’s Three Sisters and Goldoni’s La Trilogie de la villégiature staged by Alain Françon; Gontcharov’s Oblomov directed by Volodia Serre, which he subsequently adapted for Arte Television in 2017; Musset’s Fantasio directed by Denis Podalydès who later entrusted Gallienne with the title role in Hugo’s Lucrezia Borgia; and Visconti’s The Damned staged by Ivo van Hove.

As part of his activities outside the theatre company, he staged Sartre’s Behind Closed Doors (Huis-Clos) at the Tessenkai Noh Theatre in Tokyo. Further, he collaborated on the synopsis and wrote the dramaturgy for Caligula, a ballet by Nicolas Le Riche at the Opéra national de Paris, as well as the dramaturgy for Alexeï Ratmansky’s Lost Illusions at the Bolshoi. In 2017, he directed Rossini’s La Cenerentola at the Opéra national de Paris as his first lyrical piece. Between 2008 and 2010, his sketch comedy series parodying the cinema industry and entitled Les Bonus de Guillaume enjoyed great popularity on the small screen. Since September 2009, he has hosted Ça peut pas faire de mal, a weekly show on France Inter Radio where he reads great literary texts.

As a child, Guillaume Gallienne could imitate his mother to perfection. He would develop this first great performance to its full potential in an autobiographical play entitled Les Garçons et Guillaume, à table !, directed by Claude Mathieu in 2008 (for which he won the Molière Award for best male newcomer in 2010). This critical and popular success was further confirmed in 2013, when the film version garnered an audience of three million and scooped up five César Awards. He has also played in a number of feature films, such as Fabien Oteniente's Jet Set; Sofia Coppola's Marie-Antoinette; Danièle Thompson's Fauteuils d’orchestre and Cézanne et moi; Niels Arestrup's Le Candidat, Diane Kury's Sagan; Pascal Thoma's Ensemble, nous allons vivre une très grande histoire d’amour; Jalil Lespert’s Yves Saint-Laurent; and Pierre Godeau’s Eperdument. Maryline, the second film written and directed by Guillaume Gallienne opened in cinemas in November 2017.

He holds the honors of Chevalier of the National Order of Merit and Officer of the Order of Arts and Letters.