Nelly Miricioiu was born in Adjud, in Romania, where she made debut as the Queen of the Night in Mozart's Die Zauberflote. Shortly afterwards she became a soloist at the opera-house in Brasov, where her roles included Violetta in La traviata, Mimi in La boheme, Gilda in Rigoletto and Micaela in Bizet's Carmen. The winner of various international prizes, she undertook further study in Italy, and in 1981 decided to settle in Western Europe, making her home in London. Her first roles in Britain included Violetta, Tosca and Manon Lescaut for Scottish opera, with which she appeared at the opening of the 1982 Edinburgh International Festival.
The following years brought various international engagements. Nelly Miricioiu made her Convent Gerden debut in 1982 as Nedda, opposite the the tenor John Vickers, and at the Paris Opera in the three soprano roles of Les contes de Hoffmann. In 1983 she appeared in Frankfurt with Alfredo Kraus in La traviata and in the same year she made her debut at La Scala in Lucia di Lammermoor. She sang Violetta in San Francisco, and appeared also in Dallas, Philadelphia, Hamburg and in Australia.
Nelly Miricioiu made her debut at the Vienna State Opera as Manon Lescaut under the direction of Guiseppe Sinopoli in 1986, and in Rome with the role of Mimi opposite Francisco Araiza, following this with the same role in Madrid opposite Placido Domingo. 1987 brought her first Lucrezia Borgia in Montpellier and her introduction to the Berlin public in Tosca. She sang Violetta in the Arena at Verona in the summer of the same year. Her more recent roles include Gounod's Mireille and Marguerite in Faust, Jaroslavna in Prince Igor, Anna Bolena, and the Queen in Szymanowski's King Roger.