Mário Franco started music lessons at the age of 4 in Centro de Estudos Gregorianos. After one year in Lisbon Conservatory where he studied harp, singing and music theory he went on to Academia de Amadores de Música, where he continued his studies in music theory with Cristina Brito da Cruz and he started double bass lessons with Fernando Flores, and composition with Pedro Rocha as well as studying chamber music.
He subsequently became interested in jazz. and became a member of the Lisbon Hot Club. After having bass guitar lessons with António Ferro he began taking Double bass lessons with David Gausden and playing in jam sessions; also took part in workshops with Rufus Reid, Niels Henning, Orsted Pederson, Eberhard Weber, etc.
In 1986-87 attended double-bass courses given by Ludwig Streicher in Estoril and in 1988 won 1st prize in the Prémio Jovens Músicos (Young Musicians Competition); later became a member of Orquestra Sinfónica Juvenil where he worked on classical repertory with conductor Christopher Bochmann.
Also worked with conductors Silva Pereira, Miguel Graça Moura, Alberto Nunes, Roberto Perez, Michel Swierczewski, Cesário Costa...
As from 1984 plays jazz and improvised music in Portugal and abroad with musicians such as António Pinho Vargas, Mário Laginha, João Paulo Esteves de Silva, Bernardo Sasseti, Benny Lackner, Carlo Morena, Luis Barrigas, Luis Figueiredo, Dan Hewson, Carlos Martins, Tomás Pimentel, Maria João, Luigi Waites, Louis Stewart, Tommy Halferty, John Wadham, Zlatko Kaucic, Peter Guidi, Sérgio Pelágio, António Pinto, José Peixoto, Desidério Lázaro, Jarmo Savolainen, Markku Ounaskari, Jim Leff, Ralph Peterson, Jr., Samuel Rohrer, Paolo Fresu, Daniel Erdmann, Julian Argüelles, Andy Sheppard, Myra Melford, Jon Irabagon, David Binney, Peter Epstein, Ralph Towner, among others.