She entered Spanish competitions in Logrono, the Julian Gayarre competition of Pamplona, and the Viñas Competition of Barcelona, and, in Italy, the Maria Callas Competition of Naples. In 1988, she won eleven prizes in the Belvedere Competition in Vienna, including the First Prize. In 1991, she won the First Prize in the Spanish Radio Classical Music Awards by unanimous vote of the judges.
She made her debut as a professional singer while in Germany, then sang The Pearl Fishers in Pisa, Italy, and La Sonnambula in St. Gallen. In the spring of 1990, she debuted in Madrid as Susanna in Mozart
's The Marriage of Figaro to unanimous critical acclaim and wide public favor. She has also sung the role at Marsella, Montpellier, the Opéra-Bastille in Paris, and Teatro Colón in Buenos Aires.
Other of her early roles included Almirena in Handel
's Rinaldo, which she sang in Lisbon, Madrid, and Reggio Emelia; and Micaëla in Bizet
's Carmen at Monte Carlo, Madrid, and Bologna, and she frequently sings Zerlina in Don Giovanni, Antonio in The Tales of Hoffmann, and Lauretta in Gianni Schichi.
Spanish soprano Teresa Berganza
is a mentor to Bayo; the two have sung on the same stage in Rinaldo and in Pergolesi
's Stabat Mater at the Salle Pleyel in Paris. It was at Berganza's suggestion that Bayo made an unusual decision to sing Rosina in The Barber of Seville in the original lower key. Bayo has sung this part widely, including Marseilles, Montpellier, and Strasbourg. Also at Berganza's suggestion, Bayo made the unusual decision to sing the part of Fiordiligi (usually considered the lower role) rather than Despina in Così fan tutte.
She has also sung at the Metropolitan Opera in New York, La Scala in Milan, and La Monnaie in Brussels. At the last-named house, she received a rapturous reception for her performance in the title role of Cavalli's La Calisto, and returned there for a remarkable portrayal of Mélisande in Debussy
's Pélleas et Mélisande with stage direction by Herbert Wernicke which took the unusual view that Mélisande, beginning in the usual passive manner, progressively becomes mad in the course of the opera.
On the concert stage, she has sung Mahler
's Second Symphony in London under the direction of Giuseppe Sinopoli
, and the Stabat Mater of Rossini
at the Schwetzingen Festival, the Aix-en-Provence Festival, and the International Religious Week in Cuenca, Spain.
She sings Lieder recitals, but not with great frequency. (She is particularly fond of Richard Strauss
' Four Last Songs.) She has a few contemporary works to her credit, but so far has mainly remained in the Baroque through Romantic eras. She is also highly regarded in Spain as a zarzuela singer. As of the end of the twentieth century, she began to branch out into German operatic repertoire, accepting engagements to sing Pamina in Die Zauberflöte and Sophie in Der Rosenkavalier.