Örn Arnarson (born 31 August 1981 in Reykjavík) is a swimmer from Iceland.

He won his first major title in 1998 at the European SC Championships in Sheffield.

A year later, at the European SC Championships 1999 in Lisbon, Portugal, Örn Arnarson won the 100 m and 200 m backstroke swimming events.

He is the first Icelandic male swimmer ever to participate in the finals for the Olympics back in 2000 when he came 4th place in the 200m backstroke.

In late 2008, Örn Arnarson moved to Denmark, where he became the Elite Coach at Aalborg Svømmeklub Elitehold.