He grew up in and around the city of London, in Muswell Hill, and attended Highgate School, an expensive public school, with John Hassall, former bassist of The Libertines and frontman of Yeti. He currently resides in the Hampstead Heath area. He went on to form Razorlight with Carl Dalemo, Christian Smith Pancorvo (Later exchanged for Andy Burrows) and Björn Ågren. After a string of top twenty hits including "Golden Touch", their debut album Up All Night charted at number 3 in the UK, and stop-gap single "Somewhere Else" just missed out on the number 1 spot. Their self-titled follow-up album was released July 17, 2006, and debuted at number 1 in the UK album chart, giving the band their first release to top the chart. Johnny and Razorlight scored their first UK number 1 single with "America" on the 8th of October '06.

Borrell is notorious for his arrogant attitude towards the press and is famous for his proclamations of his own abilities. However, like many other artists who come across negatively in NME interviews, Borrell and supporters have accused the magazine of misrepresentation and emphasising quotes out of context. Interviewers have recently alluded to tension between Borrell and the two Swedish members of the band, one of whom claims Borrell spends little time with them.

Borrell is one of "The Dalston Set", a clique of indie notables connected to the early days of the London scene of the early 2000s, along with Dominic Masters of The Others, Pete Doherty, Carl Barât, John Hassall, and the Queens of Noize. It has been reported that he was briefly a stand-in bassist for The Libertines before they were signed, but in recent interviews he has claimed that this is not true. In Pete Welsh's Kids in the Riot, it is alleged that Borrell was sacked as The Libertines' bassist for unreliable behaviour and not turning up to gigs, but in general there is little animosity between the two bands, and Borrell remains friends with Carl Barât. The Libertines' song "The Boy Looked At Johnny" is reputedly about Borrell, and Razorlight album track "Don't Go Back To Dalston" is reputedly directed at Pete Doherty, telling him to curtail his drug habit. Similarly, the original version of 'In The Morning' features the lyrics 'I never look back in to the sun' (a clear reference to The Libertines), and 'wake him up, warm him up, put him on the stage' and 'the boy can't act his age'- believed to be about Doherty. Another Razorlight song talking about curtailing a drug habit is "Up All Night" which is largely misinterpreted as being a love song. However, Borrell's former friend Pete Doherty headbutted him backstage at the Leeds Festival in 2005. In an NME interview, Borrell recently cited that Doherty played a big part in helping him to recover from his own drug problems.

In the May 17, 2006 issue of the NME, Borrell became embroiled in a spat with fellow NME favourites The Kooks, as a result of his remarks that their music is 'shit' and the lead singer 'boring'. In an interview with the popular music magazine NME Borrell is quoted as saying "He models his style on me. And that record is the most horrible thing I've ever heard. It sounds like the band are literally rolling over, sticking their arse in the air and begging Radio 1 to fuck them. I heard their single on the radio the other day and it sounds like fucking Avril Lavigne! If he can live with himself after that production, and if he feels like he has to slag people off to keep up, then I'm sure his nights are long and those moments of doubt are really painful. So fuck The Kooks. Fuck 'em!" " implying that The Kooks had "sold out" to the commercial music industry by signing to Virgin Records and adjusting their sound to become more marketable. Ironically, Radio 1 had held a "Razorlight week" recently before that to coincide with and promote the band's second album.

In late 2006, Tim Rice-Oxley, pianist and songwriter with Keane, declared their song "The Frog Prince" to be a criticism of Borrell.[citation needed]