He went for lunch every Wednesday with his younger sister Gisèle Casadesus.
He was briefly married with the singer Micheline Ramette and had a son with her, Frédérick Casadesus, born in 1959.
In 1948, he ran a jazz club with Freddy Chauvelot, the Club Saint-Germain, which staged musicians and singers such as Django Reinhardt, Juliette Gréco, and Boris Vian.
His father, Henri Casadesus, was a musician and composer, and his mother, Marie-Louise Beetz, a harpist.
In 1939 he was drafted into the army during the Phoney War.
Casadesus played Philibert Le Roy in the 1953 film Si Versailles m'était conté de Sacha Guitry, his last film role. From 1954 to 1966, he was the Artistic Director of the Théâtre de l'Ambigu-Comique.
He was a French actor and theatre director who worked professionally in both movies and in theater, and made his first film appearance in 1930.
He studied acting at the CNSAD with Louis Jouvet and gave his debut at the theater in 1937.
From 1966 on he undertook several missions for the French Ministry of Culture.