[6] In April 2017, he guided the club to bronze in the league after beating SISU 87–72 in the third-place game.
[10] In January 2019, he received a one-game suspension for storming onto the court during live play to protest a non-call.
[13] Stjarnan opened the 2019–20 season with an 89–77 win against reigning champions KR in the annual Icelandic Super Cup.
[17] In October 2022, Arnar was hired as an assistant coach to Allan Foss with the Denmark men's national team.
[19] On 13 December 2023, he was made the head coach of Stjarnan women's team following the departure of Auður Íris Ólafsdóttir.