Formed in 2003 as ROK,[1] an all-female trio highlighting vocalist Kata (Katrína Kata Mogensen, daughter of former Kukl bassist Birgir Mogensen),[2] the group expanded in early 2004 to a 5-piece band by recruiting guitarist Arnar Pétursson and drummer Andri Bjartur Jakobsson, and adopted the new name Mammút.

Mammút's eponymous debut album was released in Iceland in 2006 on the Smekkleysa label founded by The Sugarcubes.

The follow-up album, Karkari, was released in 2008 and included "Svefnsýkt"[1] which became the band's first major hit with immense radio play and charting in Iceland.

[7] Their 2017 album, Kinder Versions, was released on 14 July 2017 following a successful fundraising campaign on Icelandic crowdfunding website Karolina Fund.

In October of 2020, Mammút released their fifth LP titled "Ride the Fire" and Valgeir Skorri Vernharðsson made his debut as the bands drummer.