[1] Þórarinn was born and raised in the town of Vestmannaeyjar, and had his debut for Íþróttabandalag Vestmannaeyja (ÍBV) in 2007 and played 12 games for the team in the 1. deild karla (men's 1st division).
Þórarinn scored 2 goals in 19 games when ÍBV won promotion to the Úrvalsdeild (Premier division) after winning the 2008 1. deild karla, and was named as the most promising player of the squad at the end of the season.
Þórarinn was on a one-month trial with Belgian team KV Mechelen in January 2009.
[3] Þórarinn scored 1 goal in 19 matches in 2009 when ÍBV were again playing in the Icelandic top league, after five years of absence.
[6] Þórarinn made his debut for the Icelandic national team when he started the friendly match against Japan in February 2012.