Gareth joined the club from Leigh East Amateur club. Although born in Scotland, Gareth lived in Widnes and travelled across to Leeds for training before being housed by the club opposite Headingley.

Gareth became a full time part of the Rhinos squad at the end of 2001 season after completing his A-Levels, which also coincided with his debut in the first team in the Rhinos penultimate game of the season at Bradford. He made one further appearance in 2002 at Salford before leaving the club.

Gareth made a try scoring debut for Scotland in 2001 against France. He followed that up later the same year when he was selected for the England U21 to tour South Africa at the end of the season. He left Leeds during the final year of his contract, in June 2002, to join the newly formed Borders rugby union team in Scotland with the hope of gaining international honours with Scotland.