In May 2009, after being dropped from first grade by the Warriors, Fien announced he has signed a three-year deal with the St. George Illawarra Dragons from 2010.
On 30 June the Warriors agreed to release Fien from the rest of his contract, and he joined the Dragons for the second half of the 2009 season.

In the opening round of 2010 he suffered a serious ankle injury which kept him out until just before the finals.
Upon his return he provided attacking options to the team and proved an invaluable player throughout the end of the regular season and finals.
He was in the 2010 premiership winning St. George Illawarra team and scored the final try of the 2010 NRL Grand Final, showcasing his dummy half skills.
He was re-signed until the end of 2013.

He retired at the end of the 2013 season.
In May 2009, after being dropped from first grade by the Warriors, Fien announced he has signed a three-year deal with the St. George Illawarra Dragons from 2010. On 30 June the Warriors agreed to release Fien from the rest of his contract, and he joined the Dragons for the second half of the 2009 season.
In the opening round of 2010 he suffered a serious ankle injury which kept him out until just before the finals. Upon his return he provided attacking options to the team and proved an invaluable player throughout the end of the regular season and finals. He was in the 2010 premiership winning St. George Illawarra team and scored the final try of the 2010 NRL Grand Final, showcasing his dummy half skills. He was re-signed until the end of 2013.
He retired at the end of the 2013 season.
Nathan Fien