Gheorghiu had success very quickly after her graduation from the Bucharest Academy in 1990, but her international career shifted into gear at England's Covent Garden, which engaged her as Zerlina in Mozart's Don Giovanni in 1992, and then as Mimi in Puccini's La bohème the same year. She received enormous critical praise for her singing there, and that house has continued to be a cornerstone of her career. In particular, her 1994 Violetta in La traviata was considered one of the finest performances of that role in many years. She made he debut at the Metropolitan Opera in 1993 as Mimi in La bohème, and while she has continued to sing there sporadically, conflicts with General Manager Joseph Volpe and later with others make her performances there irregular.
Gheorgiu quickly obtained a contract with Decca, for whom she has recorded Donizetti's L'elisir d'Amore, Puccini's La bohème, and an album called My World; her many recordings with Alagna are mostly on EMI, and include Bizet's Carmen, Verdi's Il trovatore and Puccini's La rondine. Since 1998 she has recorded exclusively for EMI, and has added Puccini's Gianni Schicchi, Gounod's Roméo et Juliette, Massenet's Werther, and an album of Verdi duets, Verdi per due, with Alagna and the Berlin Philharmonic Orchestra. At the turn of the new century, Gheorghiu was continuing to add new operas to her repertory, including Luisa Miller, Pagliacci, Faust, Lucia di Lammermoor, La sonnambula, Tosca, Lucrezia Borgia, and Simon Boccanegra. In 2000 she made a highly successful movie version of Tosca with Roberto Alagna and Ruggero Raimondi. Her recording of Manon won a Gramophone Award in 2001, and her recordings have received numerous other honors, including Diapason d'Or Awards and a Deutscher Schallplattenpreis. She has also received the highest honors awarded to Romanian citizens by the government for her contributions to Romanian culture.