McFly's name was chosen by Tom Fletcher, the band's founding member, based on his love for the American science-fiction comedy Back to the Future and Michael J. Fox's character Marty McFly.

Tom had originally auditioned for Busted, but was rejected. He then met Danny Jones at a pub where he played Richard Ashcroft songs, and the two began writing songs along with James Bourne of Busted. To complete the band, they held auditions at London's Covent Garden for a drummer and a bass player. Coincidentally, Dougie Poynter and Harry Judd both auditioned on the same day. Thus, McFly was formed. McFly's early sound was a mixture of pop rock, pop punk. Their debut single, "5 Colours in Her Hair", which was released March 29, 2004, entered the UK Singles Chart at number one in April 2004 and stayed there for two weeks.

In July 2004 their second single, "Obviously", also topped the charts. This was followed by the album Room on the 3rd Floor debuting at number one in the UK Albums Chart. The album broke records, as McFly were the youngest band to have a debut album enter the charts in the top position, beating The Beatles. The third single, "That Girl", was released on September 6, 2004 and lost the battle for the top spot to Brian McFadden's "Real To Me". It went to number three, despite topping midweek sales charts. The fourth single, Room on the 3rd Floor (the album's title track), was released on November 15, 2004 and made number five. In March 2005, McFly released "All About You/You've Got A Friend", a double A-side of their sixth and seventh singles and the first release from their second album, Wonderland, which features a 60-piece orchestra. The single reached number one for a week on March 13, 2005 and the profits from the single were donated to Comic Relief.

The video for "You've Got A Friend" was shot in Uganda, Africa, which McFly visited for the charity appeal. They completed their second arena tour in October 2005. The second single from Wonderland, "I'll Be OK", was released in the UK on the 15 August, 2005 and scored them their fourth UK number one. The album itself was released on 29 August, 2005 debuting at number one. The third single from Wonderland, "I Wanna Hold You", was released October 17, giving them their sixth top three single, missing out on number one to the Arctic Monkeys. Their fourth single, "Ultraviolet/The Ballad of Paul K" was released on 12 December, 2005 and reached number nine.

The first single from Motion in the Ocean was named, "Please, Please", released in the UK as a double A-side with the Queen hit "Don't Stop Me Now" on July 17, 2006 as the official song for Sport Relief 2006. The double A-side reached number one in the UK charts on July 23, 2006 making it the band's fifth number one single of their career.

After losing a bet to the owner of G-A-Y, McFly had to appear naked on stage as they did in their "Please, Please" video. On 14 September, 2006, it was confirmed via an email newsletter from McFly's official website, that the third album would be called Motion in the Ocean. The album was released on November 6, 2006 and reached number 6. The second release from the album, "Star Girl" was released on October 23, 2006 to promote the album.[3] "Star Girl" reached number one in its first week with 54,802 copies sold. The third release from the album, "Sorry's Not Good Enough/Friday Night" is set to be released on 18 December, 2006. "Friday Night" will also be the offical theme for a new movie called Night at the Museum, which due to be released on 26 December 2006 in the UK. McFly's style has been dubbed by themselves and others in the music business as "Nu-Pop" but is possibly more commonly considered pop or pop rock. Despite the band's pop image and reputation, there are musical differences from other contemporary boybands.

Influence is apparent from bands such as The Raspberries (particularly Eric Carmen-penned material), The Beach Boys, and The Beatles (particularly Paul McCartney-penned material). Lyrically, however, their style is closer, though not quite similar, to other contemporary guitar pop bands such as Busted and Son of Dork. McFly are often considered similar in style to the now defunct Busted, with whom they shared a record label and were generally considered to be friends. Indeed, James Bourne of Busted and Son of Dork, has had a hand in writing several of McFly's biggest hits, and Tom Fletcher had also partially written tracks for bands James Bourne has been involved with. However, though similar, Busted evidence greater influence from pop punk bands such as Blink 182 and Sum 41 than 1960s rock, in addition to their clear pop overtones. In 2005, the band guest-starred in an episode of the long-running British drama series Casualty]. They also starred in the teen comedy film Just My Luck with Lindsay Lohan and Chris Pine, which was released in the US on May 12, 2006 and in the UK on June 30, 2006.

They play themselves in the film, the soundtrack features a variety of their songs from both albums plus their latest song "Just My Luck" at the time. McFly held a concert at the London Hammersmith Apollo on May 19, 2005 which was used in the film. The Just My Luck UK premiere took place on June 28, 2006 in London.