Trabaci was born in Montepeloso (now Irsina, near Matera). Nothing is known about his early life. On 1 December 1594 he was appointed tenor at Santissima Annunziata Maggiore in Naples, but already in 1597 he must have been known as an organist and organ expert, because he was invited that year to test the organ of Oratorio dei Filippini. He served as organist there for a while, and then became, in 1601, organist to the Spanish viceroys at the Chapel Royal of Naples. The second organist was Ascanio Mayone, and Giovanni de Macque was maestro di cappella. Trabaci succeeded Macque in 1614 after the latter's death, and held the post for the rest of his life. Between 1625 and 1630 he also worked at the Oratorio dei Filippini.

Trabaci was most noted for his keyboard works, which include ricercares, canzonas and toccatas collected in two publications (Libro primo..., 1603, Libro secondo..., 1615). His bold harmonic language, with unexpected modulations to distant keys, and experiments with structure in these works influenced Girolamo Frescobaldi. He wrote 2 pieces in that experimental idiom: His "Durezze et ligature" and "Consonanze stravaganti" (1603). He also wrote numerous sacred vocal works, but these are, in general, more conservative. His 1602 book of motets, Motectorum, features advanced harmonic writing and may have influenced Carlo Gesualdo's 1603 Sacrae cantiones.

• Jackson, Roland (2001). "Giovanni Maria Trabaci". In Sadie, Stanley; Tyrrell, John (eds.). The New Grove Dictionary of Music and Musicians (2nd ed.). London: Macmillan Publishers. ISBN 978-1-56159-239-5.‎

• 21 Motectorum, per 5-6 voci e 8 voci
• 8 Rithmis, per 5 voci
• 3 Missarum et 6 motectorum, per 4 voci
• 21 Psalmarum pro vesperis et completario totius anni, cum 4 antiphonis et 4 missae, per 4 voci
• Sylvae amonicae
• 23 Hinni e 23 motetti, per 8 voci e basso continuo
• 13 Psalmi vespertini cum 6 rithmis, per 4 voci
• 13 Motetti, per 5 voci (1634)
• 4 Passionem
• 4 Messe
• Laudaum, per 4 voci
• Salmo, per 4 voci

• Il primo libro de (21) madrigali (per 5 voci
• (14) Villanelle et arie alla napolitana a 3 e a 4 (per 2-3 voci
• Il secondo libro de (20) madrigali (per 5 voci
• Madrigale per 5 voci
• Solo aria e aria, per 3 voci

• Ricercate, canzone francese, capricci, canti fermi, gagliarde, partite diverse, toccate, durezze e ligature, e un madrigale passagiato nel fine (1603, Napoli)
• Il secondo libro de ricercate & altri varij capricci [includes 100 versi sopra li Otto Finali Ecclesiastici] (1615, Napoli)

• Free scores by Giovanni Maria Trabaci at the International Music Score Library Project (IMSLP)
• Free scores by Giovanni Maria Trabaci in the Choral Public Domain Library (ChoralWiki)