In 1978 Coleman founded Killing Joke with drummer Paul Ferguson in Notting Hill, United Kingdom. The pair then recruited guitarist Geordie Walker and bassist Martin Glover (aka Youth). The group released their first single in October 1979 and their first eponymous album was released in 1980. Coleman contributed lead vocals and keyboards to the band’s songs, which are categorized as post-punk, and the music later inspired the industrial rock and metal genres.

Coleman once quit Killing Joke temporarily following a gig in 1982—the day after, he travelled to Iceland and announced his intention to become a classical composer. Ten years of studying and ongoing Killing Joke involvement later, he commenced conducting and worked with some of the world’s leading orchestras. Conductor Klaus Tennstedt described him as a “new Mahler”.

In 1995 Coleman released his first of three albums of symphonic rock music: Us and Them: Symphonic Pink Floyd, which peaked at number one in the Billboard Magazine Top Classical Crossover Albums chart, and Kashmir: Symphonic Led Zeppelin were both written and produced by Coleman with Peter Scholes conducting the London Philharmonic Orchestra. On 8 June 2007, Coleman collaborated with over 150 youth musicians in the Contemporary Youth Orchestra, based in Cleveland, Ohio, USA to perform the entirety of Kashmir: Symphonic Led Zeppelin along with additional orchestrations of Led Zeppelin’s music.

In 1999 he produced and arranged an album of Doors material for orchestra, performed by classical musicians including Nigel Kennedy and the Prague Symphony Orchestra, called Riders on the Storm: The Doors Concerto (CD released in 2000). He has worked with the New Zealand Symphony Orchestra, who have issued a CD of his Symphony No. 1 “Idavoll” with the Auckland Philharmonia Orchestra, and as composer in residence to the Prague Symphony Orchestra.