Michael Mantler was born in 1943 in Vienna, Austria, where he studied trumpet and musicology at the Academy of Music and Vienna University. In 1962 he went to the USA to continue his studies at the Berklee School of Music in Boston.

He moved to New York in 1964 and started playing trumpet with Cecil Taylor and others. During that period he was also involved in the formation of the Jazz Composer's Guild, a collective of musicians and composers, struggling for better working conditions and opportunities to present their new music without compromise. Together with Carla Bley he formed a large jazz orchestra to perform new compositions, resulting in their first recording Communication.

After the Guild discontinued its activities, he toured Europe twice during 1965/66 with the Jazz Realities Quintet, featuring Steve Lacy and Carla Bley. He then established the Jazz Composer's Orchestra Association, a non-profit organization to commission, perform, and record new compositions for jazz orchestra.

He recorded a double album of his music during 1968 with the Jazz Composer's  Orchestra and soloists Cecil Taylor, Don Cherry, Roswell Rudd, Pharoah Sanders, Larry Coryell, and Gato Barbieri. Some of this music was also performed during the "Long Concerts" at the Electric Circus in 1969.

He appeared as trumpet player on Carla Bley's A Genuine Tong Funeral, recorded by Gary Burton, and also on Charlie Haden's Liberation Music Orchestra album (1969).

He co-ordinated and participated in the Jazz Composer's Orchestra's next recording project, Carla Bley's Escalator Over The Hill (1968-71).

The problems of independently distributing the orchestra's record label led him to form the New Music Distribution Service in 1972, an organization which was to serve many independent labels for almost 20 years.

In 1973 he started WATT WORKS, a new record label devoted to the presentation of his and Carla Bley's music exclusively. He recorded No Answer, featuring Jack Bruce, for which he wrote music to the words of Samuel Beckett.

The following year he built a recording studio near Woodstock, N.Y. to escape the pressures of commercial recording studios. He received composition grants from the Creative Artists Program Service and the National Endowment for the Arts, and with the aid of a Ford Foundation grant he was able to undertake the recording of his 13 for two orchestras and piano (1975).

He wrote and recorded several more albums for WATT: The Hapless Child, with words by Edward Gorey, featuring Robert Wyatt (1976), Silence, based on the Harold Pinter play, again with Robert Wyatt (1976), Movies, with Larry Coryell and Tony Williams (1977), and More Movies, with Philippe Catherine (1980). During that period he also appeared on albums by John Greaves (Kew Rhone) and Nick Mason (Fictitious Sports), and then toured briefly with his own small group.

In 1982 he recorded Something There with Mike Stern, Nick Mason, and the strings of the London Symphony Orchestra, conducted by Michael Gibbs. Later that year he participated in a European tour and a recording (Ballad Of The Fallen) with a new edition of Charlie Haden's Liberation Music Orchestra.

Several newly commissioned compositions were performed in Cologne by the Orchestra of the West German Radio (WDR) in 1984, and the following year he composed and recorded Alien, featuring Don Preston.

From 1977 until 1985 he was also a member of the Carla Bley Band, touring extensively throughout Europe, the USA, and Japan, as well as appearing on all of the Band's recordings.

His orchestral suite Slow Orchestra Pieces was premiered by the Orchestra of the Opera de Lille in France during March 1986, and the Danish Radio Concert Orchestra commissioned a new work from him for a radio production in May 1987 in Copenhagen.

He was asked to participate in the International Art-Rock Festival in Frankfurt during February 1987, for which he formed a group with Nick Mason, Jack Bruce, Rick Fenn, Don Preston, and John Greaves. Material from this concert was later released on his Live album. The following summer he briefly toured Europe with a similar band featuring Jack Bruce and Anton Fier.

Most of 1987 was spent working on an album of songs in English, German, and French, based on the poetry of Samuel Beckett, Ernst Meister and Philippe Soupault, with Jack Bruce, Marianne Faithfull, Robert Wyatt, and the Danish Radio Concert Orchestra (Many Have No Speech). Music from this album was also performed at a concert produced by the West German Radio in Bielefeld during April 1989.

At the beginning of 1991 he left the United States, discontinuing his work with WATT, and moved back to Europe, where he now lives and works, dividing his time between Denmark and France.

A new orchestral piece was commissioned by the Austrian Donau Festival, and was premiered near Vienna in June 1991 by the Nö.Tonkünstlerorchester, conducted by Michael Gibbs, with Andy Sheppard as soloist. New compositions were also commissioned by the Danish Radio Big Band and the North German Radio Big Band in Hamburg.

His album Folly Seeing All This was recorded during June 1992 in London, and released by ECM Records in 1993. It features the Balanescu String Quartet plus other instrumentalists, and it includes new instrumental music and a setting of Samuel Beckett's last poem, written shortly before his death (What Is The Word), featuring the voice of Jack Bruce.

In 1993 he formed the ensemble "Chamber Music and Songs", featuring his trumpet plus Mona Larsen (voice), Bjarne Roupé (guitar), Kim Kristensen (keyboards), and a string quartet. Its premiere took place at the Copenhagen Jazzhouse in September, followed by a studio production at Danmarks Radio. Some of this material was eventually to appear on the Songs and One Symphony album.

His Cerco Un Paese Innocente, a Suite of Songs and Interludes for Voice, Untypical Big Band and Chamber Ensemble, with words by the Italian poet Giuseppe Ungaretti, had its premiere in concert at the Danish Radio January 1994. Featured were the voice of Mona Larsen, Mantler's Ensemble, and the Danish Radio Big Band, conducted by Ole Kock Hansen. The work was subsequently recorded in the studio and released by ECM Records in 1995. Another performance of the work took place in Palermo, Sicily, during April 1996.

His "sort-of-an-opera" The School of Languages, had its premiere August 1996 at Arken, the new Museum of Modern Art in Copenhagen. Participants included singers Jack Bruce, Mona Larsen, Susi Hyldgaard, John Greaves, Don Preston, Karen Mantler, Per Jørgensen, and Robert Wyatt. Its recording was released as a double-CD by ECM Records in the Fall of 1997 under its new title The School of  Understanding. The work was again presented during November 1997 at the Hebbel Theater in Berlin.

A large orchestral piece, One Symphony, commissioned by the Hessischer Rundfunk, was premiered November 1998 by the Radio Symphony Orchestra Frankfurt, conducted by Peter Rundel. Its recording was released by ECM in early 2000 together with previously recorded material featuring Mona Larsen and the "Chamber Music and Songs" Ensemble (Songs and One Symphony) interpreting songs set to texts by Ernst Meister.

Hide And Seek, an album of songs with words by Paul Auster (from his play by the same name), for chamber orchestra and the voices of Robert Wyatt and Susi Hyldgaard, has been released by ECM Records March 2001. Theatrical productions of the work, in collaboration with Rolf Heim (who has previously worked with Mantler on The School of Understanding performances), were created in the Spring of 2002 in Copenhagen and Berlin.

His Concerto for Marimba and Vibraphone (originally commissioned by Portuguese percussionist Pedro Carneiro in 2001), was premiered at the Hessischer Rundfunk in March 2005 with the Radio Symphony Orchestra Frankfurt, conducted by Pascal Rophé.

During September 2006 Porgy & Bess in Vienna presented a series of retrospective portrait concerts with his "Chamber Music and Songs" ensemble

In recognition of his life's work he received several Austrian awards: the State Prize for Improvised Music, the Prandtauer Prize of the City of St.Pölten (where he spent his early youth), and the Music Prize of the City of Vienna.

Released November 2006, the anthology Review (recordings 1968 - 2000), traced his unique musical path during more than 30 years of recordings for JCOA, WATT and ECM.

He appeared at the JazzFest Berlin in November 2007 with his Concertos project, featuring the Kammerensemble Neue Musik Berlin under the direction of Roland Kluttig. A studio recording of Concertos with soloists Bjarne Roupé (guitar), Bob Rockwell (tenor saxophone), Roswell Rudd (trombone), Pedro Carneiro (marimba and vibraphone), Majella Stockhausen (piano), Nick Mason (percussion), and Mantler on trumpet, was released by ECM during November 2008.

His next CD For Two, a series of duets for guitar (Bjarne Roupé) and piano (Per Salo), was released by ECM during June 2011.

New works were commissioned and performed by the Max Brand Ensemble, conducted by Christoph Cech (Chamber Music Eight, Tage der Neuen Musik, Krems, Austria, 2012) and by the Chaos Orchestra, conducted by Arnaud Petit (Oiseaux de Guerre, featuring singer Himiko Paganotti, Forum Blanc-Mesnil, France, 2014).

During September 2013 Porgy & Bess in Vienna presented his Jazz Composer's Orchestra Update project, featuring the Nouvelle Cuisine Big Band, conducted by Christoph Cech, with soloists Michael Mantler (trumpet), Harry Sokal and Wolfgang Puschnig (saxophones), Bjarne Roupé (guitar), David Helbock (piano) and the radio.string.quartet.vienna. The program included a complete re-working of all the pieces from the original 1968 album, as well as of even older material from as early as 1963, never before performed or recorded. A selection of recordings from these performances was released by ECM Records during November 2014.

The complete Jazz Composer's Orchestra Update project was performed live several times during 2015/16: at the Moers Festival and at the North Sea Jazz Festival in Rotterdam (with the Nouvelle Cuisine Big Band) and at the German Jazzfestival Frankfurt (with the hr-Bigband), as well as in Portugal at the Lisbon Jazz em Agosto Festival (with the Orquestra Jazz de Matosinhos)

Comment c'est, a song cycle for voice and chamber orchestra, featuring the French singer Himiko Paganotti and the Max Brand Ensemble, conducted by Christoph Cech, was premiered in Vienna with two concerts at Porgy & Bess in September 2016. Its recording was released by ECM Records during November 2017.

He subsequently continued working on further orchestral reinterpretations of older works, very selectively choosing material for more "updates" of different musics that were particularly dear to him and that he thought should have a new (and different) life. The result was a series of suites (HideSeek, Alien, Cerco, Folly, TwoThirteen) for a larger orchestra, conducted by Christoph Cech, presented with three concerts during September 2019, again at Vienna's Porgy & Bess. Its recording, CODA - Orchestra Suites, was released in July 2021 by ECM Records.

The compositions from his Concertos album were performed September 2021 in Vienna and again in Graz at the Big Band Bang Festival in 2022, with the Janus Ensemble and soloists, conducted by Christoph Cech.

Songs for bass clarinet (Gareth Davis) and trumpet soloists, vocal and brass ensembles and percussion, with texts by Samuel Beckett, Ernst Meister, Giuseppe Ungaretti and Michael Mantler, were premiered October 2022 at the Jazz Goes to Town festival at Hradec Králové in the Czech Republic, followed by a repeat performance at Porgy & Bess in Vienna.

The New Songs Ensemble featuring John Greaves (voice), Annie Barbazza (voice), Michael Mantler (trumpet), Gareth Davis (bass clarinet), Bjarne Roupé (guitar), David Helbock (piano) and the radio.string.quartet - Bernie Mallinger (violin), Igmar Jenner (violin), Cynthia Liao (viola), Sophie Abraham (cello) - performed new versions of the same songs at Porgy & Bess in Vienna during September 2023. At that occasion Mantler was awarded the Austrian Cross of Honour for Science and Art, First Class. A recording of this concert was released on CD (Sempre Notte - Live Songs) by Dark Companion Records in September 2024.