The band originally formed as Dolmen in 1989, and after briefly taking the name Azathoth, they became Absu in 1991.The original members were Equitant Ifernain (guitars, bass, lyrics) and Shaftiel (guitars, vocals).

After recording two demos and releasing an EP, they were joined by Proscriptor McGovern (Russ R. Givens – drums, vocals, lyrics), David Athron Mystica (guitars), and Black Massith (keyboards, synth, sequencing).

After releasing their first album, Barathrum: V.I.T.R.I.O.L., in 1993, Absu narrowed their line-up to a three piece when David Athron Mystica and Black Massith left. For live performances, they recruited the help of Mezzadurus (from the Philadelphia black/thrash band Bloodstorm) and recorded as a three piece with Shaftiel and Proscriptor sharing vocal duties and Proscriptor taking over keyboard and synth duties as well.

The band stayed with this line-up for some time. With their second album, The Sun of Tiphareth (1995), the band explored Sumerian, Mesopotamian, and Celtic mythology. The band’s third album, The Third Storm of Cythraul (1997), drew inspiration mainly from Celtic mythology, and continued their intellectual approach. Over the next four years, Equitant and Proscriptor worked with the ambient group Equimanthorn and Absu’s sole release was the EP In the Eyes of Ioldánach (1998).
In 2001, Absu recruited a new second guitarist, Kashshapxu. The band released their fifth album that year, Tara, which continued the Celtic theme of Cythraul and Ioldánach, and featured bagpipes on the title track.[4] The album is considered the band’s masterpiece, and is described by McGovern as a concept album:
“The album is presented in a chronicled assembly dividing it into two phases: ‘Ioldánach’s Pedagogy’ and ‘The Cythrául Klan’s Scrutiny’.

Certain goals and objectives were finally accomplished with ‘Tara’, through exploration of our ancestral attributes and channeling divisions of pure magic within our minds and souls”.
This line-up was short-lived as soon after recording Tara, Equitant left due to musical differences (however, he and Proscriptor still collaborate on other projects to this day). Shortly after that, Proscriptor severely injured his hand in an accident, which required surgery to repair his hand. After almost a year of healing and therapy, he was ready to play again, but Shaftiel no longer had any interest in Absu and Kashshapxu had also left the band due to musical differences. Proscriptor then put Absu on hold and decided to work on other projects.

During this period he auditioned for Slayer, but Slayer eventually went with their original drummer, Dave Lombardo. In 2005, Proscriptor and Equitant put together a collection of rare, live and unreleased Absu recordings and released it under the title Mythological Occult Metal: 1991–2001 based on the suggestion of a fan.
With Absu still on hold, Proscriptor continued to work on other projects including Equimanthorn (with Equitant and members of The Soil Bleeds Black; dark ambient music), Proscriptor (his own project of neo-folk/classic rock fused music), and Starchaser Network (with Equitant and Victorious; electronic art/rock band). Additionally, he was the drummer/vocalist for Melechesh for six years (1999–2005, although he still contributes lyrics and vocals) and has done session work with Judas Iscariot, Thornspawn, and Magnus Thorsen. Proscriptor also has his own record label, Tarot Productions.
In May 2007, Prosciptor finally announced the addition of Vastator Terrarum and Aethyris MacKay to the band. In early 2008, Absu announced they had signed with Candlelight Records for future recordings, but that they would release a 7″ EP through Relapse Records. That EP was Speed N’ Spikes, a limited series featuring their first new material in seven years. In March 2008, Vastator Terrarum left and was replaced by Zawicizuz (formerly of the bands Infernal Oak, Rape Pillage Burn, and Bleed the Son). In October 2008, the band added ex-Panzram member Ezezu on bass and vocals, after completing the recording of their self-titled album, released on February 16 (Europe) and February 24 (USA), 2009, on Candlelight Records.

In September 2009, Zawicizuz left Absu and was replaced by Vis Crom of Rumpelstiltskin Grinder, Woe and XXX Maniak. The band then embarked on a European tour with Pantheon I, Razor of Occam and Zoroaster.
In November 2010, Absu announced that they would be doing a six-date U.S. tour with Immortal in February 2011 as a three piece as Aethyris MacKay has left to join Pantheon I. After this tour, Absu entered the studio to record their next album, titled Abzu (released in October 2011), followed up with a tour.
In 2012, they released a single through Adult Swim (Williams Street Records) titled “Hall of the Masters” and later a video was produced for the song, their first official promotional video in 14 years (the previous being “Mannannan” in 1998). The band is currently in pre-production for their next album, titled “Apsu”.