As a child he suffered from polio, spending four years in hospital up to his sixteenth birthday. It was in hospital he first heard Bob Dylan, inspiring him to a career of words and music. At ten he received a guitar from his parents, and he played violin with the school orchestra. He left the Haberdashers' Aske's Hatcham College with no A levels.
In 1968 he got a job as an accountant with the Daily Express from where he progressed to become a reporter in a number of local Essex newspapers for a duration of three years. Later, he returned to London to work for the East London Advertiser.
He first started out playing in bars and clubs in the early seventies, mainly at folk venues on open-mike nights where he joined the band Odin. He also busked around London on the Underground and Portobello Road. While performing with Odin he met Jean-Paul Crocker, with whom he formed Cockney Rebel in late 1972.
Cockney Rebel went on to release The Human Menagerie and The Psychomodo before splitting up in 1974. However, Harley carried on with drummer Stuart Elliot renaming the band to Steve Harley & Cockney Rebel, with whom he had much more success. From the next album The Best Years Of Our Lives came the massive number one single "Make Me Smile (Come Up and See Me)" which is one of the most played records in British broadcasting history.
He had two more hits during the mid 1970s with "Mr Raffles" and "Here Comes The Sun" which were both top 20 hits, but he didn't have any further major successes, and in the 1980s he all but faded from the public eye, relocating to America. He was set to star as the Phantom in the London premiere of The Phantom of the Opera, and recorded the promotional single of the title song, but was replaced close to rehearsals by Michael Crawford. He has stated in an interview that he would have done a better job than Crawford , though public opinion seems to doubt this .
In the early 90s he released several albums as Steve Harley (without Cockney Rebel). His songs "Sebastian," "Tumbling Down," and "Make Me Smile" were included in the Todd Haynes' 1998 rock musical Velvet Goldmine. In 2005 The Quality of Mercy was released under the Steve Harley & Cockney Rebel name, and Harley began touring more frequently.
In 1999 Harley began presenting a BBC 6 Music programme The Sounds of the Seventies. This moved to BBC Radio 2 in 2000, however the show has been dropped for the foreseeable future and the last programme was aired on 27 March 2008.