Martin Mayes was born in Dumfries, Scotland, on May 6, 1952, and studied music at the University of York before moving into London's experimental music scene in the 1970s. He became a founder member of the London Musicians' Collective and, through his studies, connected with Derek Bailey and Evan Parker's Music Improvisation Company and with John Stevens's Spontaneous Music Ensemble, the two ensembles that defined British free improvisation in that decade. His earliest discography-verified credits date from this period: the Spontaneous Music Orchestra's SME + = SMO (1975) and a 1976 Obscure Records session with Jan Steele and John Cage.

In 1982 Mayes moved to Turin, and has lived there ever since, a stretch of more than four decades that makes him one of the longest-resident foreign musicians in the Italian jazz scene. All About Jazz described him at one point in his career as "living in Italy for twenty years," and by the time the Italian Instabile Orchestra was assembled for the Festival di Noci in 1990, Mayes was already established enough in Turin's improvised-music circles to become the orchestra's founding, and to date only, non-Italian member. He has stayed with the orchestra through every incarnation since, including its 2026 return at the Torino Jazz Festival to perform Plays Ellington under Giancarlo Schiaffini's direction, more than three and a half decades after the orchestra's first concert.

His discography-verified work runs from British free improvisation's first generation through the length of the Italian avant-garde jazz scene the Instabile Orchestra came to represent. He recorded with Giorgio Gaslini on Masks (1992), with Paolo Damiani's ensemble on Song Tong (1997), with Gaetano Liguori on the Kurosawa-inspired suite Ronin (2000), and repeatedly with Giancarlo Schiaffini as a member of the brass ensemble Phantabrass across a run of releases from 2006 to 2012. He appears on four Cecil Taylor recordings made with large European ensembles, including In Berlin '88 (1989) and The Owner Of The River Bank (2003), the latter a meeting between Taylor and the full Italian Instabile Orchestra, and on the orchestra's 2008 session with Anthony Braxton, Creative Orchestra (Bolzano) 2007. More recently he has recorded with soprano saxophonist Gianni Mimmo (Prossime Trascendenze, 2017) and alongside British free-improviser Evan Parker on Live At Angelica 2018 with the Setoladimaiale Unit.

Alongside his jazz and free-improvisation work, Mayes maintains a parallel practice in early and medieval repertoire for the natural, valveless horn, and in recent years has developed solo and small-ensemble performances on the alphorn (corno delle Alpi), including a 2017 walking-performance project along the Dorsale Orobica-Lecchese trail in Lombardy and a 2018 solstice performance at San Glisente. As a leader, his discography runs from the self-released Solo (1995) and Solo Requiem Per Guelfo (1996) through Unique Horn (1997, Random Acoustics, executive-produced by Georg Graewe), and includes a 2013 group release as The Five Roosters, Cinque Galli In Fuga (Per Tacer Del Sesto). Italian saxophonist Mario Schiano once called him "the whirling dervish of the horn," and London's City of London Festival has described him as "an architect of musical imagination."

Mayes's playing sits at the intersection of British free improvisation and Italian avant-garde jazz, carrying the vocabulary he absorbed from the Music Improvisation Company and the Spontaneous Music Ensemble into decades of work inside the Italian Instabile Orchestra and its members' side projects. His discography is heavily weighted toward Free Jazz, Free Improvisation and Avant-garde Jazz on the Discogs style tags of his own and his collaborators' releases, and his most sustained working relationships have been with musicians who share that idiom: Cecil Taylor's large European ensembles, Giancarlo Schiaffini's Phantabrass brass group, and the Italian Instabile Orchestra itself, whose ECM debut Skies Of Europe (1995) drew public praise from Ornette Coleman. Outside that core, Mayes keeps a genuinely separate secondary practice in early and contemporary classical repertoire for the natural horn, and, since the 2010s, in solo alphorn performance staged outdoors in the Alps; neither displaces the jazz and free-improvisation work that accounts for the large majority of his recorded output.