Didier Courtois was born in Charleroi, and studied Graphic Artss at the Saint-Luc in Liège. He worked as an archeologist for several years, before turning to comic art, starting with the Loup Durand adaptation 'Les Cavaliers aux Yeux Verts' for Claude Lefrancq Éditeur in 1992. During the same period, he made a lot of illustrations for Tremplin magazine. He teamed up with writer Denis Lapière to make 'La Race des Seigneurs' for Dargaud in 1995, and assisted Magda on the artwork of her 'Charly' series.
Between 1998 and 2005, he worked with Frank Giroud on the historical series 'Louis Ferchot', reviving characters created by Giroud and Jean-Paul Dethorey in the series 'Louis la Guigne' in the 1980s. Courtois also provided the artwork for an installment in Giroud's series 'Le Décalogue - Les Fleury-Nadal' in 2009.