As a player and coach, he was a member of six national championships with Njarðvík.
[1] In 1983, he became a player-coach for Njarðvík and led the team to three straight national championships.
[4] In 2005, Gunnar returned to the sidelines as an assistant coach to Einar Árni Jóhannsson[1] with the Njarðvík's team that went on to win the 2006 national championship.
[5] From 1974 to 1981, Gunnar played 69 games for the Icelandic national basketball team.
[6] Gunnar is the father of former Icelandic national team player Logi Gunnarsson.