Guilhem Bec studied industrial design, but eventually turned to creating comics. He moved to Brussels in 1991, where he began his career working for Studio Peyo. He joined the magazine Spirou in 1991, where he illustrated editorial pages, as well as short comics with scenarios by Salma, Gilson, Mazan and Zidrou. Between 1992 to 1994, he drew the series 'La Tribu des Epithètes' for the magazine (text by Gilson). Back in France, Guilhem worked for Le Journal de Mickey and Minnie Mag for four years, illustrating articles and game pages, as well as the series 'Entre-Nous'. He also took on illustrating advertising folders.
From 1995 to 1997, he drew the series 'Le Lézard ne Dort que d'un Oeil' with scripts by Jean-Paul Rouland. He went back to Belgium and Spirou in 1998, illustrating six novels based on Lucien De Gieter's 'Papyrus' and the series 'Sélim le Marin'. In 2001, he teamed up with writer Pierre Veys and created the series 'Space Mounties' Lombard. In 2008 he started the heroic fantasy series 'Zarla' with scripts by Janssens in Spirou. Guilhem is a member of the Atelier Sanzot.