Walker started his career at Huddersfield in 2010 where he played sporadically only making 6 appearances for the Giants. He spent most if 2011 on loan at Barrow where he made 16 appearances. In 2012 Walker was sent out on loan again, this time to Swinton where he played 7 times scoring twice.
Hull Kingston Rovers
Walker was sold to Hull KR in 2013 after claiming that he wanted a new challenge, and also that Hull KR is a big club. He scored his first try for Hull KR against London Broncos. Walker play 107 times for Hull KR until he rejected a reduced contract when the club was relegated after losing the Million Pound Game to Salford.
St Helens
After departing Hull KR, Walker signed for St Helens for the 2017 season. His time at St Helens was unsuccessful and he failed to see out the end of the season at the club as he was sold to Wakefield Trinity after making only 9 appearances for the club scoring one try.
Wakefield Trinity
After an unsuccessful start to the season at St Helens, Walker signed for Wakefield on a 2½-year deal but only played 7 times before being dismissed when he tested positive for cocaine.
Walker signed a 2-season contract with Salford commencing at the completion of his drugs ban in March 2019. He played in the 2019 Super League Grand Final defeat by St. Helens at Old Trafford. Early in the 2020 season Salford granted him a release from his contract by mutual consent.
International career
In October 2013, Walker was selected to play for Scotland in the 2013 Rugby League World Cup. He made his International début against Tonga in the group stage. In October and November 2014, Walker played in the 2014 European Cup competition. He played in all of Scotland's games and scored a try in their fixture against France. In October and November 2015, Walker played in the 2015 European Cup competition.
Private life
On 27 January 2016, Walker was charged with two offences of attempting to engage in sexual activity with a child, with a court appearance due later in February of that year. He remained available for selection. All charges were ultimately dismissed. In August 2017, Walker was suspended for testing positive for cocaine usage during a drugs test.
