A Hornby Panthers junior in the
Canterbury Rugby League competition, in 1995 Kidwell played in the
Lion Red Cup for the
Canterbury Country Cardinals. He then joined the
Canterbury-Bankstown Bulldogs in 1996 and also made the
1996 Junior Kiwis that year. He made his first grade début on 17 August 1997 in round 17 for the
Adelaide Rams against Canberra at Canberra Stadium. In 1999, Kidwell joined Parramatta and played in the clubs heart breaking preliminary final loss to Melbourne that year where the club was leading 16-6 but lost 18–16. Kidwell was selected for the
New Zealand team to compete in the end of season
1999 Rugby League Tri-Nations tournament. In the final against
Australia he played from the interchange bench in the Kiwis' 22–20 loss. Between 2001 and 2002, Kidwell played for Warrington in the
Super League. In 2002, Kidwell joined the Sydney Roosters, he played 18 games for the club but missed out on playing in the clubs
2002 NRL Grand Final victory over the
New Zealand Warriors. In 2003, Kidwell joined Melbourne playing a total of 103 games for the club including the
2006 NRL Grand Final where the Storm lost to the Broncos 15–8. In 2006, Kidwell signed a pre-contract agreement to represent the
South Sydney Rabbitohs until 2009. In the
2007 pre-season, it was announced that Kidwell would be co-captain of the South Sydney Rabbitohs, along with
Peter Cusack for 2007. In April 2007, Kidwell was ruled out for the season after suffering a freak accident at home where he tripped over one of his children and injured his knee. At the end of 2007 Kidwell was named in the
Melbourne Storm team of the decade. After failing an alcohol test on 2 May 2008, the South Sydney club stripped Kidwell of his co-captaincy and four others who failed were relegated to the bench for their Sunday match against North Queensland. Kidwell retired from rugby league at the end of the 2009 season. ==Representative career==