[3][4] Þórir played for Selfoss handball team until 1986, when he moved to Norway to study at the Norwegian School of Sport Sciences.

Shortly after moving to Oslo in 1986 to further his education he was hired as the head coach of Elverum men's team.

[11] In December 2016, he guided the team to gold at the 2016 European Women's Handball Championship despite losing his mother the day before the tournament started.

[2] In September 2024, Þórir announced that the current season would be his last as head coach of the national team.

[17] On 21 March 2017, Þórir was made a Knight 1st Class of the Royal Norwegian Order of Merit.