Born in Paris, Pierre Lacroix should initially take over his parents small shop in Marly-le-Roi. But Lacroix ambitions 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 made some advertising illustration artwork for clients like Gestetner.
After being forced to work in Germany during World War II, he returned to France and settled in Vésinet as an independent advertising artist. 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 scripts by writers like Maric, René Lortac and Roland De Montaubert between 1947 and 1988. In 1953 and 1954, he filled in for Pellos on three stories of 'Les Pieds Nickelés', and he additionally created 'Pat et Patricia' for Fillette in 1954.
During the 1960s, Lacroix's 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 drew two stories with 'Aggie' for Fillette, replacing Gérard Alexandre.