Born on April 22, 1935, in Crescentino, Province of Vercelli, Italy, Cossotto attended the TurinAcademy of Music and studied with Mercedes Llopart. She made her operatic debut as Sister Matilde in the world premiere of Poulenc's Dialogues of the Carmelites in 1957 at La Scala in Milan. Her international debut was at the 1958 Wexford Festival as Giovanna Seymour in Donizetti's Anna Bolena. Her Covent Garden debut was in 1959 as Neris in Cherubini's Médée, with Maria Callas in the title role. A 1962 performance of the lead inLa favorita at La Scala led to wider fame and she made her American debut in the same role in 1964 at the Lyric Opera of Chicago and as Amneris at the Metropolitan Opera in 1968. Between the seasons of 1967–68 and 1988–89, Cossotto gave 148 performances at the Met. She was considered an expert in portrayals of major mezzo/contralto roles in mid-19th-century Italian opera such as Favorita , Amneris, Azucena, Eboli, Preziosilla, Maddalena, Ulrica and Laura. She also portrayed Carmen, Mozart's Cherubino, Urbain in Meyerbeer's Les Huguenots, Bellini's Romeo and Marfa in Khovantschina. In 2005, Cossotto celebrated her 70th birthday with a performance of Suor Angelica at the Théâtre Royal in Liège, Belgium. Cossotto was married to the Italian bassIvo Vinco for over 40 years. They had a son. According to the book Opera'', "She and Giulietta Simionato were the leading Italian mezzo-sopranos of the 1960s and 1970s. She won plaudits in the annals of operatic history for her wonderful vocal timbre, her perfect singing technique, and the ease with which she could master different registers. Besides singing the great mezzo roles, she also took the outstanding alto parts of the Italian operatic repertoire." Apart from mezzo and alto roles, Cossotto also sang soprano roles traditionally sung by mezzos such as Santuzza and Adalgisa. She sang Adalgisa next to the Normas of Callas, Joan Sutherland, Montserrat Caballé, Leyla Gencer, and Elinor Ross Her repertory at the Met included Amneris, Eboli, Adalgisa, Santuzza, Azucena, Dalila, Carmen, Principessa and Mistress Quickly.
