The Italian mezzo-soprano Giulietta Simionato (born 12 May 1910) is a famous opera singer whose career spanned the mid-1930s until her retirement in 1966. Simionato was much admired for vibrant singing, both in dramatic roles and comic ones. She appeared in a number of productions and made a number of recordings with Maria Callas.

Simionato was born in Forlì , Italy. She studied in Rovigo and Padua and made her operatic debut at Montagnana in 1928. In 1936, she made her debut at La Scala and appeared there regularly between 1936 and 1966. She made her debut at the Royal Opera House, Covent Garden in 1953, where she likewise appeared regularly between 1963 and 1965. In 1959, Simionato made her debut at the Metropolitan Opera.

Simionato also appeared at the Edinburgh Festival (1947), the San Francisco Opera (1953), the Teatro Nacional São Carlos (1954), the Lyric Opera of Chicago (1954-61), the Vienna State Opera (from 1956), and the Salzburg Festival.

Simionato had a large repertory including Rossini's Rosina and Cinderella, Charlotte in Werther, and Carmen. She retired in 1966.