Although Arnalds started out as a drummer for a number of Icelandic metal bands, he has emerged as a composer, multi-instrumentalist and producer. He is in the premier league of creators of neo classical work which includes subtle elements of pop and electronic music, and this activity commenced with his work for the Erased Tapes label. He also formed the experimental techno group Kiasmos with Janus Rasmussen. His subsequent output has gained real favour for film and television soundtracks, with the BBC series Broadchurch being a particular highlight. He has gone on to receive an Emmy nomination for his theme to the Apple TV mini series ‘Defending Jacob’.