After studying architecture, Monpoix began his career in industrial design in the 1940s, working for the Airborne company. He also taught industrial design at the Ecole des Beaux-Arts in Paris in the 1960s.
His designs are characterized by simplicity, elegance and functionality, and have been widely used in public spaces, workplaces and private residences. Among his most famous creations are the "Ellipse" chair for Airborne, the "Gilda" armchair for Steiner, and the "Stork" armchair for Arflex.
Over the course of his career, Monpoix won numerous awards and distinctions, including the Médaille d'or de la Société des artistes décorateurs in 1957 and the Grand Prix national de la création industrielle in 1984. His creations can be found in the collections of many museums, including the Centre Georges Pompidou in Paris and MoMA in New York.