He was the founder of the Centre de Musique Baroque de Versailles. He was the artistic adviser of 1987 to 1996. He has also been a producer of musical programs for Radio France since 1974. He was known for writing the biography of Jean-Baptiste Lully, Lully ou le musicien du soleil (Éditions Gallimard, 1992).
Beaussant won the 1993 Grand Prix du roman de l'Académie française for his novel Héloïse.