The song was released as the third and final single from In Rainbows on 23 September 2008. It was released through the Radiohead Remix website in the form of 'stems', individual parts of the song (e.g. vocals, guitar, piano) for fans to remix, as with 'Nude'.

The song was listed at #254 on Pitchfork Media's 'Top 500 songs of the 2000s'.

In 2001, Radiohead performed a song with the working title of 'Reckoner' in George, Washington. This song, also known as 'Feeling Pulled Apart by Horses' after a part of the lyrics, was a fast-paced, 'thrashy' rock song.

In 2005, at a Trade Justice Movement rally where he also played 'Nude', Radiohead singer Thom Yorke performed this early version of 'Reckoner' on acoustic guitar. Yorke was later asked about the band's plans for 'Reckoner', and he declared it 'dead and buried'.

The song, in either form, was not played on the 2006 Radiohead tour where most In Rainbows material was introduced live. However, the song title was included in the final track listing of their seventh album.

Late in 2007, members of Radiohead gave an interview to BBC Radio 1 in which they explained that the new 'Reckoner' in fact came out of an attempt to record the earlier song with that title. Late in the sessions, Yorke and Greenwood tried adding a coda to the original version of the song, and eventually the band decided to abandon everything except the new coda, which became 'Reckoner'.
The pre-coda, original version of Reckoner was eventually reworked by Thom Yorke (with Jonny Greenwood) and released as a solo effort, bearing the title Feeling Pulled Apart By Horses.

'Reckoner' is featured in the 2008 film Choke based on the novel by Chuck Palahniuk, and in the 2010 Warren Miller film, 'Wintervention'. Gnarls Barkley have played a cover of the song numerous times on tour.