Killoffer started making comics in 1981, and took courses in comics in Paris from Georges Pichard and Yves Got. In 1987 he launched the magazine Pas Un Seul with Jean-yves Duhoo. He subsequently participated in Globof and Lynx. Together with Lewis Trondheim, Stanislas, Jean-Christophe Menu, David B. and Mattt Konture he founded l'Association in 1990. Some of his material was published in Lapin. Also, l'Association has published three of his albums: 'Billet SVP', 'La Clef des Champs' and '676 Apparitions de Killoffer'. In 2000, he worked with scriptwriter Jean-Louis Capron on the political tale 'Viva Pâtâmach'! for Éditions du Seuil.
Killoffer has also contributed to Psikopat, and he has done illustrations for the papers Libération and Le Monde. He is Il a été également publié dans la revue Psikopat. Il illustre régulièrement des articles dans les quotidiens Libération et Le Monde. Additionally, his works 'Wie man sich bettet' and 'Der Schlüssel zur Freiheit'. were published by the German publishing house Reproduct. Since 2006 he is the new illustrator of the children's book series 'Fantômette' for Bibliothèque Rose.