The band comprises Beth Gibbons (vocals), Geoff Barrow (multiple instruments, production), and Adrian Utley (guitar).

[8][9] Portishead's debut album, Dummy (1994), fused hip-hop production with an atmospheric style reminiscent of spy film soundtracks and yearning vocals from Gibbons.

Geoff Barrow and Beth Gibbons formed the band after meeting during a coffee break at an Enterprise Allowance course in Bristol in February 1991.

A DVD of Portishead's Roseland Ballroom performance, with substantial extra material including many early musical videos, was released in 2002.

In August 2006, the band posted two new tracks on its MySpace page (called "Key Bored 299 03" and "Greek Jam"), described by Barrow as "doodles".

[29] On 18 May 2008, Barrow expressed Portishead's enthusiasm for recording new material on their website's blog, stating that he "can't wait to write some new tunes".

[31] Whilst the album had yet to materialise, on 9 December 2009, the band released the song "Chase the Tear" for Human Rights Day to raise money for Amnesty International UK.

[34] The band also headlined and curated the line-up for two All Tomorrow's Parties music festivals entitled I'll Be Your Mirror, in London at Alexandra Palace on 23 and 24 July.

[36] Barrow stated that he realised a "boyhood fantasy" when Chuck D of Public Enemy joined the band onstage at the "ATP I'll Be Your Mirror" festival curated by Portishead in Asbury Park, NJ in October 2011.

He contributed his verse from the Public Enemy song "Black Steel in the Hour of Chaos" over Portishead's single "Machine Gun".

The Chicago Tribune hailed the concert and noted: "horror-movie accents—Gothic organ, guitar lines thick with menacing reverb, spooky theremin—ensured a certain darkness".

[43][44][45] Additionally, Portishead produced a cover of ABBA's song "SOS" for the soundtrack to the movie High-Rise which had a Gala screening at the London Film Festival on 9 October 2015.

[47] On 22 June 2016, Portishead released a video for "SOS" that recontextualized the song in the wake of the then-recent murder of member of parliament Jo Cox and the Brexit vote.

[49] Lead singer Beth Gibbons would also appear on rapper Kendrick Lamar's song "Mother I Sober" from the album Mr. Morale & the Big Steppers, released on 13 May.