Mafalda Favero enrolled at the Bologna Conservatory when she was seventeen, where she studied singing with Alessandro Vezzani and also attracted the attention of the composer Franco Alfano. At Cremona in 1925, under the name of Maria Bianchi (“Mary White”), she substituted for another singer at short notice as Lola / Cavalleria rusticana; but her formal operatic stage debut took place in 1927 at the Teatro Regio, Parma as Liù / Turandot, followed by Elsa / Lohengrin and Margherita in Boito’s Mefistofele.
In 1928 Favero was engaged by Toscanini to sing Eva in Die Meistersinger von Nürnberg at La Scala, Milan in the production mounted to mark the thirtieth anniversary of his principal conductorship there. She sang at La Scala continuously until 1949 in a considerable variety of roles, being especially identified with the lyric repertoire with an emphasis upon verismo roles.