Ari started his career at Valur. At sixteen, he went to SC Heerenveen in the Netherlands where he spent two seasons. He was released at the end of 2005 when he could not make the first team. He returned to Valur where he played half a season before signing with Allsvenskan club BK Häcken. Although relegated to the Swedish second tier, the club competed in the UEFA Cup qualifiers the following year because of their fair play ranking. Häcken managed to progress into the main competition after Ari scored the winning goal against Scottish club Dunfermline Athletic F.C.. Häcken failed to gain promotion, and he signed with Allsvenskan club GIF Sundsvall at the end of the year. At the start of the 2012 season he became captain of the club.