Arnalds began his music career playing drums for different hardcore / metal bands like ‘Fighting Shit’ and ‘Celestine’. While playing for one such band and supporting the German extreme metal band ‘Heaven Shall Burn’ during their Icelandic tour, Arnalds gave them a demo of his songs he developed at home. The band called him after a few months and offered him to write intros and outros of their new album, however with only the piano/strings elements. This led him to compose and record the intro ‘Echoes’ and two outros ‘Rísandi Von’ and ‘Deyjandi Von’ for the band’s album ‘Antigone’ that released on April 26, 2004 and became a success in Europe.
His work in ‘Antigone’ impressed Erased Tapes Records founder, Robert Raths resulting in release of Arnalds’ first studio album ‘Eulogy for Evolution’ on October 1, 2007. It included eight tracks, all written by him. The following year he released the EP ‘Variations of Static’. He wrote the intro ‘Awoken’ for the January 25, 2008 released album of ‘Heaven Shall Burn’ titled Iconoclast (Part 1: The Final Resistance).He also toured with Icelandic avant-rock band Sigur Rós. According to reports, he sold out The Barbican Hall in London.
In April 2009, for seven days in a row, Arnalds composed and released one track a day, each of which were made available within 24 hours from foundsongs.erasedtapes.com. The first one was released on April 13, 2009 and the collection of the tracks titled ‘Found Songs’ was also released later that year. Same year he composed a track for the ballet ‘Dyad 1909’.
He formed the Faroese-Icelandic minimal, experimental techno duo, Kiasmos, along with Janus Rasmussen in 2009. Same year they came up with an EP titled ‘65/Milo’ in collaboration with fellow label colleague Rival Consoles. Kiasmos released their eponymous debut album on October 27, 2014 which received critical acclaim. Other works of the duo include Erased Tapes EPs ‘Thrown’ (2012), ‘Looped’ (2015), ‘Swept’ (2015) and ‘Blurred’ (2017).
Meanwhile Arnalds’ next album ‘...And They Have Escaped the Weight of Darkness’ released in April 2010. That year he went on an Asian Tour organised by China-based music company Split Works. It was well-received. The following year on October 3, he again started composing and releasing one track a day, for seven days, with each track being made available each day at livingroomsongs.olafurarnalds.com/. The collection of the tracks titled ‘Living Room Songs’ was later released on December 23, 2011.
He furthered his fame in 2012 with his score for Sam Levinson's black comedy-drama film ‘Another Happy Day’. That year he also collaborated with German pianist Nils Frahm to release the EP ‘Stare’. The 2012 released dystopian science fiction-adventure film ‘The Hunger Games’ featured his song ‘Allt varð hljótt’, while the track Til enda was used in a trailer of the 2012 sci-fi action film ‘Looper’.
In 2012, he got into a partnership with the newly formed Mercury Classics record label. Such partnership resulted in release of Arnalds’ third studio album ‘For Now I Am Winter’ in February 2013. It was his first ever released work that included vocals. It was used in the pilot of the period drama television series ‘Masters of Sex’ in 2013.
He composed the score and end-credits track of the ITV aired British serial-crime drama television series ‘Broadchurch’. It fetched him the 2014 BAFTA TV Craft Award for Best Original Music. He also composed the score for the 2013 independent Christian drama film ‘Gimme Shelter’. His songs also featured in different seasons of ‘So You Think You Can Dance’.
He collaborated with German-Japanese pianist Alice Sara Ott and released the album ‘The Chopin Project’ through Mercury Classics on March 16, 2015. It included original compositions of Arnalds based on motifs from Chopin apart from recordings of Chopin piano compositions. The work on the album started as a dedication to Arnalds’ grandmother with whom he would listen to Chopin’s work whenever the two visited each other.
’Trance Frendz - An evening with Ólafur Arnalds and Nils Frahm’, a live improvisational film; ‘Stare’; and his collaborative EPs with Frahm titled ‘Life Story Love and Glory’ and ‘Loon’ were compiled and released as the double-CD ‘Collaborative Works’ in 2015. He composed music for the British serial crime drama television series ‘Broadchurch’. Full release of his work on ‘Broadchurch’ happened in 2015.
He collaborated with director Baldvin Z and seven artists and travelled seven locations in Iceland over seven weeks to develop the album ‘Island Songs ‘ that released through Mercury Classics on August 12, 2016. Audio and video of each of the seven tracks were released each week with the last one ‘Doria’ being released on August 8, 2016.
He returned to solo work with his fourth official solo album‘re:member’, an experimental work that released in 2018. It featured his avant-garde musical system called Stratus, a distinctive custom-built software that included two self-playing, semi-generative player pianos that are triggered by the main piano played by Arnalds. ‘re:member’ debuted at #8 on the Billboard Top Heatseekers chart.