[2] Viðar spent the majority of his career with Höttur and was a key player for the club when it was promoted to the Úrvalsdeild for the first time in 2005.
[6] In 2009, he signed with Laugdælir, where he averaged 18.3 points,[7] but returned to Hamar after the season.
[8] In 2011, Viðar was hired as the head coach of Höttur.
[10] In March 2020, Höttur won the 1. deild for the third time under his command after the rest of the season was canceled due to the coronavirus outbreak in Iceland.
He was the head coach of the Icelandic national U-18 team from 2017 to 2018.