Parisian artist and writer Jean-Louis Janssens studied Decorative Arts as well as Graphic Arts, and started out working in the communication field. He became one of the main writers of humorous comics for Spirou during the 1990s and 2000s. He began with several short stories for artists like Olis, David Deth, Bercovici and Gazzotti from 1993. He later created several (shortlived) series, such as the superhero parody 'Cosmic Patrouille' with artist Mauricet, 'Les Maîtres du Monde' with Olivier Saive, 'Nationale Zéro' for Éric Maltaite and 'Télé-Emplettes' for Fabrizio Borrini.
Between 2000 and 2007, he helped Serge Ernst with the scenario-writing of the series 'Les Zappeurs', and he wrote the final books in the series 'Billy the Cat' for Péral between 2005 and 2007. Spirou also ran his series 'Karma' (created with Fabrizio Borrini) between 2006 and 2008, and 'Zarla' (with Guilhem) since 2007. Both have been published in book format by Dupuis. In 2001 and 2002, he created the gag strip 'Charlotte', for which he also did the artwork.
From 2009, Janssens has also been writing for other publishers, creating 'Beauté Fatale' with Benoît Ers for Vents d'Ouest and 'Planet Ranger' with Julien/CDM for Lombard. He is also present at Bamboo with the series 'Livraison Express' (with Jean-Marc Krings), 'Les Scientiflics' (with Serge Carrère) and 'Le P'tit Coach' (with Curd Ridel). In addition, Janssens does illustration work for Bayard Presse and Le Journal de Mickey.