The band was formed in 2001 by drummer John Alfredsson and singer Johannes Eckerström. After a turbulent start, the line up settled in the fall of 2003 and stayed the same for ten years. In February 2013 guitarist Simon Andersson left the band, being replaced by Tim Öhrström.
Avatar has seen several European tours as supporting act for Impaled Nazarene (May 2006), Evergrey (October - November 2006), In Flames (March 2007), Obituary (January - February 2008), Hardcore Superstar (October - November 2009), Warrior Soul (March - April 2010), Dark Tranquillity (October - November 2010), Helloween (December 2010 - January 2011) and Avenged Sevenfold/Five Finger Death Punch (December 2013) as well as an American tour with Lacuna Coil/Sevendust (February 2013). The band has performed on several of the larger music festivals in Sweden, e.g. Sweden Rock Festival, Arvikafestivalen and Storsjöyran.
Schlacht, the second album by Avatar was released in October 2007, reaching spot 27 on the Swedish album chart. Björn Gelotte from In Flames contributed a guitar solo on the track Letters From Neverend.
The band's third album, the self-titled Avatar, was released in Sweden in November 2009 reaching the 36th position on the national album chart. Most of the year up until the release of the album was spent in the studio. In January 2010 the band signed with Sony Music for the German and Swiss release of the latest album on March 26, 2010. In April of the same year a deal was signed with the Japanese label Art Union, for a May 19 launch of the album.
On January 25, 2012 the album Black Waltz was released in Europe. It reached position 25 on the album list in Avatar's native Sweden. The album was released in the US on February 14.
In the fall of 2013 the band spent a month in Thailand recording for a new album, planned for release in March 2014.
In 2013, after the wife of the singer of the band Device had pregnancy problems, they had to back down from the tour and Avatar was picked by Avenged Sevenfold to replace Device and continue to tour with them and Five Finger Death Punch.