Cotrubas was born in Galati, Romania. In 1952 she moved to Bucharest to study at the Scoala Speciala de Musica school for the musically gifted. Ctrubas debuted with the Bucharest Opera in 1964, and soon became well known, appearing in productions throughout Europe in the 1960s.
Ileana Cotrubas was contracted as member of Vienna Opera starting in 1970. In 1973 she joined the Lyric Opera in Chicago then in 1975 to La Scala in Milan, and then to New York's Metropolitan Opera in 1977.
Her singing was known for her strikingly beautiful voice, atheletic stamina, and finesse with opera in many different languages.
Cotrubas retired from public singing in 1990; she continues to teach, giving master classes and coaching promising young singers.