Giovanni Battista Mazza trained at the 'Giuseppe Verdi' Conservatory in Milan: organ, piano, composition and conducting.
He attends various master classes.
Winner of the first prize at the International Competition "Giovani Organisti d'Europa" (Pisa 1986), he is active, both as a soloist and as a conductor, in various European countries, in the United States and in Latin America.
He plays in many international festivals and, as conductor, he collaborates with important orchestras and institutions such as Fondazione Arena di Verona, Accademia del Teatro alla Scala, Orchestra Milano Classica, Orchestra de I Pomeriggi Musicali and Orchestra Sinfonica Giuseppe Verdi of Milan, Accademia Filarmonica Romana, Teatro Comunale of Ferrara, Orchestra Sinfonica di Sanremo, Orchestra del Teatro Olimpico di Vicenza, I Solisti Aquilani, Südwestdeutsche Philarmonie, Dniepropetrovsk Opera House, Kalisz Philharmonic Orchestra, Vidin State Philharmonic Orchestra, Macedonia Philharmonic Orchestra, Bacau Symphony Orchestra, Panama National Symphony Orchestra, Berry College Symphonic Ensemble of Atlanta.
Numerous first performances of works and compositions by contemporary composers, often dedicated to him.
He records for various radio and television stations and is present in the recording field with recordings dedicated to Bach and the Italian 20th century.
Particularly interested in the little-visited Italian repertoire, he brings to light and re-proposes unpublished and incomplete pieces by Ottorino Respighi and other composers of the time in their first modern performance.
He transcribes for orchestra compositions by Aldo Finzi, recorded on monographic CDs under his direction and published by Preludio, and pieces by Arvo Pärt for the Universal publishing house.
He teaches organ and organ composition at the Conservatorio "Giuseppe Verdi" in Milan, where he also holds courses on the performance practice of contemporary music. He holds lectures and masterclasses at Berry College University of Georgia.