Born in Paris, Pierre Lacroix should initially take over his parents small shop in Marly-le-Roi. But Lacroix passions were with drawing and not commerce. Therefore, at the age of 17, he became the apprentice of Louis Forton, author of 'Les Pieds Nickelés', who was a client of the shop. Forton introduced him to the S.P.E. (Société Parisienne d'Édition) and in 1930, he started making illustrations for Le Pêle-Mêle. He subsequently did some advertising illustration work, among others for Gestetner.

After being forced to work in Germany during World War II, he settled as an independent advertising artist upon his return in France. In 1944, his name appeared in the magazine Jeunes Gars-Mon Avenir with the character 'Criquet'. He also returned to the S.P.E. and took over the Louis Forton creation 'Bibi Fricotin' from Gaston Callaud, which he illustrated from 1947 until 1988. In 1953 and 1954, he made three stories of 'Les Pieds Nickelés', replacing Pellos, who was ill.

During the 1960s, his work also appeared in the magazines Lisette ('Mick et Mack' and 'Domi et Pascaline'), Fripounet ('Nelly'), Le Journal de Bibi Fricotin and Le Journal des Pieds Nickelés ('Razibus Zouzou', 'Les Chahuteurs'). With writer Montaubert, he made an album of 'Placide et Pomalo' and four albums of 'Coussie et Coussa' (Ed. Albon). In 1974, he took over the series 'Aggie' from Gérard Alexandre for a period of two stories.