Wilkin started his career at Hull Kingston Rovers before being signed by St. Helens. Wilkin soon broke into the first team and has been dubbed by some as one of the most promising running backs in the game. By the age of 24, Wilkin had impressed many and played in some high octane matches. Wilkin was called in to the Tri Nations squad in 2005 but did not feature in the competition.
However the 2006 season was a new high point in Jon’s career. He was a key member of the treble-winning team as Saints won the 2006 Challenge Cup where he played with a broken nose. St Helens reached the 2006 Super League Grand final to be contested against Hull FC and Wilkin played at second-row forward in Saints' 26-4 victory. He was included in the 25-man squad for the 2006 Tri-Nations Tour of Australia and New Zealand. Wilkin made his international debut from the bench at the Aussie Stadium, Sydney on 4 November 2006 against Australia. He came off the bench in two further games in that series, the first against New Zealand in Wellington and the second against Australia in Brisbane. The icing on the cake for Wilkin and St. Helens came when they won the BBC TV Sports Personality of the Year Team of the Year award, with Daniel Anderson taking the Best Coach honour. Wilkin (L) was recognised for his good season by being named in the 2006 Super League Dream Team. As 2006 Super League champions, St Helens faced 2006 NRL Premiers the Brisbane Broncos in the 2007 World Club Challenge. Wilkin played at loose forward in the Saints' 18-14 victory. Jon was awarded community volunteer of 2008 at a ceremony in Manchester. Jon said of his achievement "All those hours of helping others is part of my job". Jon went on to thank, amongst others, author Rudyard Kipling whose poem 'If' is a prominent influence in his life. He played in 2008's Super League XIII Grand Final defeat by Leeds. Wilkin was selected for the England squad to compete in the 2008 Rugby League World Cup tournament in Australia.Group A's first match against Papua New Guinea he played from the interchange bench in England's victory.