After studying with such prestigious names as Rina Malatrasi, Rodolfo Celletti and Leyla Gencer, Denia Mazzola began her career in 1982, gaining immediate recognition for her incredible dramatic talent, which she continued to demonstrate in such intensly emotional female leading roles such as Lucia di Lammermoor, Lucrezia Borgia, Anna Bolena, Violetta Valery, Esclarmonde, Elisabetta I in Roberto Devereux, Zazà, Parisina, Clitemnestra and Medea.

In these roles she appeared at the most important theatres all over the world (Venice, Florence, Genoa, Milan, Frankfurt, Zurich, Paris, Vienna, New York, Rio de Janeiro, Houston, etc...) and has frequently taken part in season's opening night. She has often been guest of La Scala in Jommelli's Fetonte, Pergolesi's Lo frate 'nnammurato (under Riccardo Muti), Puccini's La Bohème (as Musetta and Mimì both under Gianandrea Gavazzeni) and La Rondine, in Berlioz's Les nuits d'etè and in Cantelobue's Chants d'Auvergne.

Thanks to her love for research, she became, with fourteen roles in her repertoire, one of the leading figures of the Donizetti-Renaissance. Her versatility as an artist is widely demonstrated by her ability to sing both opera and operetta (Leoncavallo's La reginetta delle rose in Genova, Bizet's Le docteur miracle in Florence and Lehar's La vedova allegra in Genova) in a repertoire ranging from Purcell to Martucci, from the most sophisticated french repertoire to verismo. In July 1995 she sang Nedda in I Pagliacci in Genova and opened the 1995 Donizetti Festival with the revival of Caterina Cornaro, receiving the 5th Donizetti Prize.  She opened the 95 concertistic season in S.Carlo's theather of Naples with Martucci's La canzone dei ricordi, followed by a Semiramide in Bilbao.

At the beginning of 1996 she sang Ciadi in the rediscovered Balilla-Pratella's L'aviatore Drò in Lugo di Romagna, followed by Poulenc's Les dialogues des Carmelites (Nouvelle Prieure) in Verona. In march she appeared as Mimì in Palermo and then in Montemezzi's L'amore dei tre Re in Wien. Other engagements included, Bohème, videotaped at the Puccini Festival in Torre del Lago as well as Silvano and Sì for the Mascagni Festival in Livorno (both operas will be released on cd by Agorà). She then opened Seville's opera season as Alice in Verdi's Falstaff, returning to Genoa for Bohème and adding two new roles to her wide repertoire: Mascagni's Iris in Catania, and Fiordiligi in Mozart's Così fan tutte in Palermo. She sang Caterina Cornaro at the Wien Konzerthaus, Wagner's Wesendock Lieder and Isoldes Liebestod in Parma, then making her debut as Suor Angelica in Catania. In 1998 she celebrated Donizetti's bicentenary with Roberto Devereux in Bilbao.

This was followed by her acclaimed debut Norma in Messina and L'amore dei tre re in bregenz (on cd by Koch Schwann). She recently starred in a Gala Concert in Pretoria, and sang Iris for the centenary of the opera in Livorno, directed by Lindsay Kemp (on cd by Agorà). This was followed by her triumphal appearence at the Queen Elizabeth hall in London as Helène in Les Vepres Siciliennes and by her debut in Mascagni's Parisina at the Montpellier Festival (due to release on cd along with her recital of Mascagni Heroines). She also appeared in Hamburg for a triumphal performance of La Traviata; Donna Elvira in Don Giovanni (full version); L'amore dei tre re at the Bayerisches Rundfunks in München. She has recently played Manon in Manon Lescaut at Bellini in Catania, Clitemnestra in Cassandra at Montpellier Radio Festival, that has also seen her triumphal protagonist of Cherubini's Medea. The year 2000 ended with the original version of Busoni's "Turandot" in Sassari. She recorded for Ricordi, Koch Schwann, Agorà doschi, Nuova Era, Actes Sud.