His first mature work, the one-act opera buffa, Amelia Goes to the Ball, was premiered in 1937, a success that led to a commission from the National Broadcasting Company to write an opera especially for radio, The Old Maid and the Thief, the first such commission ever given. His first ballet, Sebastian, followed in 1944, and for this he wrote the scenario as well as the score. After the premiere of his Piano Concerto in 1945, Menotti returned to opera with The Medium, shortly joined by The Telephone, both enjoying international success.
Menotti writes the text to all his operas, the original language being English in every case, with the exception of Amelia Goes to the Ball, The Island God, and The Last Savage, which were first set to Italian words. Recent operas include The Singing Child (1993) and Goya (1986), written for Plácido Domingo and given its premiere by The Washington Opera. In the summer of 2004 Domingo reprised the role at Vienna's Theater an der Wien. Menotti's most recent vocal works are Jacob's Prayer (1997), a commission from the American Choral Directors Association, Gloria, written as part of a composite Mass celebrating the 1995 Nobel Peace Prize, For the Death of Orpheus, with a premiere by the Atlanta Symphony Orchestra led by Robert Shaw in November 1990, and Llama de Amor Viva, premiered in April 1991. A trio for the Verdehr Trio received its world premiere at the Spoleto Festival on Menotti's 85th birthday in July 1996.
In addition to the numerous operatic works, Menotti has enriched the artistic world with ballets, including Errand into the Maze (in the 2005 repertory of the Martha Graham Dance Company), and The Unicorn, the Gorgon, and the Manticore; Pastorale for Piano and Strings (1934);Poemetti, a suite of piano pieces for children (1937); The Hero (1952), a song on a text by Robert Horan; and Canti della Lontananza, a cycle of seven songs (1967). He also wrote the libretti to Samuel Barber's operas Vanessa and A Hand of Bridge.
1958 saw the opening of Menotti's own festival, the Festival of Two Worlds, in Spoleto, Italy. Devoted to the cultural collaboration of Europe and America in a program embracing all the arts, the Spoleto Festival has gone on to be one of the most popular festivals in Europe. The festival literally became "of two worlds" in 1977 with the founding of Spoleto USA in Charleston, South Carolina, which he led until 1993 when he became Director of the Rome Opera. Well into his 90s he continued to direct opera at Spoleto and elsewhere. His 1996 Spoleto production of Amahl was filmed for commercial release. During the 2005-06 season The Consul will be produced at Teatro Regio in Italy; performances in the 2004-05 season included productions at the Arizona Opera and in Zurich, Switzerland.
In 1984 Menotti was awarded the Kennedy Center Honor for lifetime achievement in the arts. He was chosen the 1991 "Musician of the Year" by Musical America, inaugurating worldwide tributes to the composer in honor of his 80th birthday. His music has been published by G. Schirmer since 1946.