Gareth had a highly successful amateur career competing for New Zealand before turning Professional and earning his PGA Tour of Australasia card in 2002. In his rookie year on Tour, Gareth finished T3 at the Australian PGA Championship, his first tournament as a Professional. In the same year he went on to record his first Professional victory at the Scenic Circle Hotels Golf Classic.
Gareth has also competed on the European Challenge Tour where in 2007 he won the AGF-Allianz Open des Volcans - Challenge de France which then secured him his European Tour card for 2008. Despite five top-25's finishes Gareth was unable to retain his card for the 2009 season. More recently Paddison has also competed on OneAsia and the Japan Golf Tour. In 2014 Gareth won the Lexus of Blackburn Victorian PGA Championship.
Gareth's best results have mainly been on the PGA Tour of Australasia where he won both the Adroit Insurance Group Victorian PGA Championship in 2012 and the Scenic Circle Hotels Dunedin Class in 2002. In 2017, Gareth has had 3 top 10 finishes at the Fiji International, the NZ PGA Championship and the Victorian PGA Championship.
- Represented New Zealand as an amateur in 2000 Eisenhower Trophy, 2001 Four Nations Cup and 2001 Southern Cross Cup.
- Represented New Zealand as a Professional at the 2011 World Cup with Michael Hendry.
- Left-handed Professional golfer