[6] Kjartan played for nine seasons in the Icelandic top-tier Úrvalsdeild karla, mostly with Stjarnan.
[13] In 2012, Kjartan was hired as head coach for Stjarnan women's team.
[15] Kjartan served as an assistant coach with Stjarnan men's team during the 2014–2015 season,[16] helping it win the Icelandic Basketball Cup in 2015.
In May 2022, Kjartan was hired as the head coach of Álftanes men's team.
[19] Kjartan was a member of the Bæjarins bestu hip hop group in the 2000s and performed under the name Kájoð.