Pierre Bailly was born in Algeria, but he soon moved to Belgium. He studied at the comics section of the Saint-Luc Institute in Brussels, under Pierre Pourbaix and Marc Sevrin. There, he met Vincent Mathy, with whom he did a small editorial project. He then studied graphics in La Cambre and published his first comic with the independent publisher Rêve-en-Bulles in 1993 ('Anguille Crue').
With Denis Lapière, he had a brief appearance in Spirou with 'La Baleine de Gaana' (1994), which was followed by the album 'La Saison des Anguilles' at Dargaud (1996). Bailly and Lapière then launched the children's comic 'Ludo'. While Bailly draws the adventures of 'Ludo', Vincent Mathy provides the art for the virtual world of 'Inspecteur Castar', Ludo's favourite comic character. In a more adult fashion, Bailly and Lapière made 'Adamgorok' for the Aire Libre collection in 1993. In 2007, Bailly teamed up with Céline Fraipont to create 'Petit Poilu' for the collection Puceron.