Menotti was born into an affluent family in Cadegliano, Italy, in 1911. His mother Ines was a good musician who often hosted small concerts and recitals at the family villa. Gian Carlo was a musical prodigy, and by the age of 11 he had written an opera (The Death of Pierrot). When he was 14, he entered the Milan Conservatory. At 17, he departed for the United States with his mother, who, with support from family friend Arturo Toscanini, saw to his enrollment at the Curtis Institute of Music in Philadelphia. There he began composition studies with Rosario Scalero and met composer Samuel Barber, who became his lover and with whom he shared a home for over 40 years. As a student, Menotti spent much of his time with the Barber family in Westchester, PA.
He graduated from Curtis in 1933 and soon began work on his first mature opera: Amelia al Ballo. It was premiered at Curtis in 1937 with such success that it was taken up by the Metropolitan Opera the following year. In 1939, NBC commissioned The Old Maid and the Thief, his first opera in English and the first opera written specifically for radio broadcast.
The only failure of Menotti's early career was The Island God (1942), commissioned by the Metropolitan Opera. During the war years, he wrote his Piano Concerto in F and a full-length ballet Sebastian. His chamber opera The Medium was premiered in May 1946 and had a run of 212 performances on Broadway during the following season, paired with his one-act comedy The Telephone. The Consul (1950), the composer's first full-length opera, considered by many to be his masterpiece, also had a long Broadway run, and it won the Pulitzer Prize and the New York Drama Critic's Circle Award. The story, inspired by the plight of individuals trapped in European totalitarian states after the Second World War, was originally intended for a Hollywood film, one of several unproduced scripts the composer wrote for MGM.
NBC commissioned Menotti to write Amahl and the Night Visitors, the first opera created especially for television, for live broadcast on Christmas Eve 1951. It became his most popular work, has received thousands of productions, and is the most frequently performed American opera. He wrote his most ambitious opera, The Saint of Bleecker Street (1954), for Broadway, and it brought him his second New York Drama Critics' Circle Award, his second Pulitzer Prize, and a New York Music Critics' Award. His choral ballet The Unicorn, the Gorgon and the Manticore, which he described as a madrigal fable, received its premiere in 1956. His third full-length opera, Maria Golovin, was written for the 1958 Brussels World's Fair. It had a very brief run on Broadway and has not enjoyed the popularity of his earlier operas.
In 1958, Menotti and conductor Thomas Schippers established the renowned Festival of Two Worlds in Spoleto, Italy. The festival consumed much of his creative energy, and although he wrote 16 more operas and many orchestral and choral works, little of the music he wrote since its founding has had critical or popular success. He stepped down as Spoleto's director in 1967, though he remained its president. In 1977 he established Spoleto USA in Charleston, SC, and served as its director until 1993. He was briefly director of the Rome Opera beginning in 1993. Menotti received the Kennedy Center Honor for lifetime achievement in the arts in 1984, and he was Musical America's Musician of the Year in 1991.