[3] She made her screen debut in 1970, when she was cast in Jean Rollin's La vampire nue, appearing alongside her twin sister,[3] Catherine, in the first of several roles which she would appear with her sister.

Both films were intended to feature Catherine, but when she fell pregnant, Rollin had to find new girls to pair Marie-Pierre with.

Castel would continue to appear in a number of Rollin's films, such as, the comedy, Tout le monde il en a deux, and one of his most successful works, Lèvres de sang,[3] which starred Jean-Loup Philippe and Annie Belle.

Castel accepted work in several of Rollin's pornographic films, when the director was facing financial difficulty at the time while trying to make up the budget for his intended projects, turning to the adult film industry as a viable option; featuring in Phantasmes, Douces pénétrations, Introductions and in her final collaboration with Rollin, Suce moi vampire, which was an extended pornographic version of Lèvres de sang, with the hardcore scenes shot and inserted into the film in 1976.

Her final acting appearance was in the 1977 Francis Girod film, René la canne, starring Gérard Depardieu, Sylvia Kristel and Michel Piccoli.