Like their last release, Favourite Worst Nightmare (2007), Humbug was released first in Japan, on 19 August 2009, followed by Australia, Brazil, Ireland and Germany, on 21 August 2009. It was then released in the UK on 24 August 2009, in the US the following day and in Greece on 31 August. The release preceded the band's headline performances at the Reading and Leeds Festivals at the end of that week.
The band started writing songs for the album towards the end of summer 2008, with lead singer Alex Turner suggesting that the inspiration for the first few guitar riffs came while the band were attending the Latitude Festival in Suffolk. Tracks were written through the end of 2008, with recording taking place around the band's touring schedule towards late 2008 and early 2009.
Co-produced by Josh Homme of Queens of the Stone Age, Eagles of Death Metal and Them Crooked Vultures, the album was wholly recorded in the United States. Homme-produced tracks recorded in Los Angeles and the Mojave Desert alongside New York recordings produced - as per the second album - by James Ford, who also produced the album The Age of the Understatement by Turner's side-project The Last Shadow Puppets.
The first single off the album was "Crying Lightning". It was released on 6 July, when it was played on BBC Radio 1 and was available for download from iTunes after midnight that day.
On October 4, 2009 the band's official website announced the second single from the album would be "Cornerstone". The Cornerstone B-side's were announced as being "Catapult", "Sketchead" and "Fright Lined Dining Room".
As with Whatever People Say I Am, That's What I'm Not and Favourite Worst Nightmare, Humbug was well-received by critics. Billboard stated that the band "justif[ies] the hype by shifting its best qualities into different, equally dazzling shapes," while The Record Review noted that with Humbug, the Arctic Monkeys proved themselves to be a "band that surpasses most of its colleagues in terms of songwriting and performance ability.". In his positive review of the album, Joe Tangari of Pitchfork Media noted that "Humbug isn't better than either of its predecessors, but it expands the group's range and makes me curious where it might go next. It also demonstrates a great deal of staying power for a band that could have imploded before it ever got this far.". While overall response was positive, the album was criticized by some for not containing the same hooks and clever lyrics that the band had become known for, with Spin calling the album "accomplished, but not particularly infectious."