Born in Ardwick, Manchester to Irish parents, Marr formed his first band at the age of 13. He was part of several bands along with Andy Rourke before forming the Smiths with Morrissey in 1982. The Smiths attained great success and were critically acclaimed, with Marr's jangle pop guitar style becoming distinctive of the band's sound, but separated in 1987 due to personal differences between Marr and Morrissey. Since then, Marr has been a member of the Pretenders, The The, Electronic, Modest Mouse and the Cribs, and has become a prolific session musician, working with names such as Talking Heads and Hans Zimmer. He released his first solo album, titled The Messenger, in 2013, followed by his second, Playland, in 2014. His autobiography, Set the Boy Free, was published in 2016.
Voted the fourth best guitarist of the last 30 years in a poll conducted by the BBC in 2010, Phil Alexander, editor-in-chief of Mojo, has described Marr as "arguably Britain's last great guitar stylist". In 2013, NME honoured Marr with its "Godlike Genius" award, hailing him: "Not content with rewriting the history of music with one of the world's greatest ever bands, the Smiths, he's continued to push boundaries and evolve throughout his career, working with some of the best and most exciting artists on the planet."
Marr was born John Martin Maher on 31 October 1963 in Ardwick, Manchester, to Irish emigrants from Athy, County Kildare. The family moved to Wythenshawe in 1972. From 1975, he attended St Augustine's Catholic Grammar School, which in 1977 merged with other schools to form St John Plessington High School.
At the age of 13, Marr's family moved him to a new neighbourhood in Manchester where he met up with "a bunch of guitar players" which "changed his life". The Cult guitarist Billy Duffy was in a high school band that practiced across the street from Marr new house, and Marr would hang out listening to them rehearsing. Marr formed his first band, the Paris Valentinos, at the age of 13, with Andy Rourke (who had gone to the same high school as Duffy) and Kevin Williams (who later became an actor, known as Kevin Kennedy), performing for the first time at a Jubilee party in Benchill in June 1977, playing Rolling Stones and Thin Lizzy covers. In 1979, he played a single gig at Wythenshawe Forum with a band called Sister Ray and re-united with Rourke in a band called White Dice. White Dice entered a demo-tape competition organised by the NME and won an audition for F-Beat Records, which they attended in April 1980 but were not signed.
In October 1980, Marr enrolled at Wythenshawe College, serving as President of the school's Student Union. White Dice dissolved in 1981. Marr and Rourke then formed a funk band, Freak Party, with Simon Wolstencroft on drums. Around this time, Marr first met Matt Johnson, with whom he would later collaborate.
By early 1982, Freak Party had fizzled out, being unable to find a singer. Marr approached Rob Allman, singer in White Dice, who suggested Steven Morrissey, a singer with the short-lived punk band the Nosebleeds. Marr approached a mutual friend asking to be introduced and they visited Morrissey at his house in Kings Road, Stretford in May.