Walker joined Gloucester for the start of the 2006/07 season on a 2-year contract from World Fighting Bull. He made 24 appearances in all competitions during his debut season, scoring 220 points. This included 2 tries against Bath & Bristol. In his second season he made 23 appearances in all competitions, scoring 96 points. He scored 2 tries against Leicester Tigers and Bourgoin. On 22 May 2008, Walker signed a 2-year extension to his contract.
On 13 September 2008, Walker played a key role in Gloucester's victory at The Rec. He scored 1 try, 1 conversion, 2 penalties & 1 drop-goal to help Gloucester to a 21–17 victory.
On 16 May 2009, having played Nine games and scored 74 points whilst on loan to Worcester Warriors from Gloucester, it was officially announced that Walker had signed a 2-year deal with the Warriors, after being released from his contract by the Cherry & Whites. This new deal would keep Walker at the Worcester Warriors until 2011.
During his loan spell with Worcester Warriors Walker famously helped the Warriors achieve a huge derby double over local rivals Gloucester by kicking Worcester to victory both at Sixways and Kingsholm.