He was of a noble family and was trained as an officer in the Piedmontese Guard, where his father was a general. At the age of 26 he left the army for political reasons, travelled to Paris, and began to study voice with Giovanni Marco Bordogni at the Paris Conservatory. Before his debut in 1838 at the Paris Opéra in the title role of Giacomo Meyerbeer's Robert le diable, he was instructed by the composer. He was immediately successful, signed his contract simply “Mario,” and was popularly known thereafter by that name alone.

In 1839 Mario made a triumphant debut in London as Gennaro in Gaetano Donizetti's Lucrezia Borgia opposite Giulia Grisi (Grisi, Giulia), a famous Italian soprano who became his life-long companion. He made his Paris debut at the Théâtre-Italien as Nemorino in Donizetti's L'elisir d'amore. For the next 30 years he was a principal singer of romantic parts in Paris and London, also appearing in St. Petersburg (Russia), New York City, and Madrid. His most admired early roles were Nemorino, Ernesto, and Gennaro. Later he was acclaimed for his Almaviva, which he sang more than 100 times in London, the Duke of Mantua, Raoul, and Faust. In 1871 he gave his farewell performance as Fernand in Donizetti's La favorita at Covent Garden in London, and after a concert tour of the United States he retired to Rome where his fortunes so declined that friends arranged a benefit recital for him in 1880.