Marie-Belle Sandis studied in Paris and Lyon. Her first engagement took her to the Opéra de Lyon as a member of the ensemble.

This was followed by engagements in Toulouse and at the Théâtre Royal de la Monnaie in Brussels (title role in Ravel’s L’Enfant et les sortilèges). In 2002–03 she was engaged in Gelsenkirchen, where she sang Béatrice in Béatrice et Bénédict and Ramiro in La finta giardiniera.

She has been a member of the National Theatre ensemble since 2003–04 and made her debut as as Dorabella, Donna Elvira, Vitellia, Cecilio, Annio, Silvia, Octavian, the Composer, Hansel, Charlotte in “Werther”, Giulietta in The Tales of Hoffmann, the Actress in La Voix humaine, Rosina, Adalgisa, Giova...