He is the son of Alexandre Pierre Étienne Rapin, a painter, and Marie Véronique Maurice. 

A student of Jean-Léon Gérôme and Eugène Grasset, he was close to Henri Bellery-Desfontaines and gradually moved towards the decorative arts, designing Art Nouveau style furniture which evolved, from the 1910s, towards the Art Deco style. From 1905 to 1930, he was artistic director of the trunk-maker Moynat for which he illustrated the catalogs, created the visual identity (brand and motifs) and designed some objects. Strongly involved in the revival of applied arts that characterizes his generation, he was appointed from 1920 to 1934 artistic director of the school of the Committee of Ladies of the Central Union of Decorative Arts and artistic adviser to the National Manufacture of Sevres.