Oxford United King started his career with
Oxford United and made his debut on 1 May 2001 against
Port Vale in the last competitive match to be played at the
Manor Ground. He would leave the club having made just four appearances.
Barnet King signed for Conference side
Barnet in 2003. While with the club he would win the league title in 2004–05. King was transfer listed by
Barnet at the end of the 2006–07 season, for which he was named player of the year, to avoid him leaving on a free transfer a year later.
Gillingham He was signed by
League Two side
Gillingham for £200,000 on a three-year deal in June 2007. This fee could however rise to £250,000, depending on appearances and whether Gillingham were to achieve promotion to the
Football League Championship. The following season King would achieve promotion with the Kent side, playing the full 90 minutes as they defeated
Shrewsbury Town 1–0 in the
2009 League Two play-off final, a game in which he was named Man of the Match. He was named Gillingham's Player of the Year for the season as well as being voted into the
Professional Footballers' Association League Two team of the year. However, during a pre-season friendly against
Bromley, King suffered an ankle injury which kept him out of the entire 2009–10 season. The injury also carried over to the beginning of the 2010–11 season. and made his debut in a 2–1 defeat at
Burton Albion on 3 September. He made two further appearances before the loan was extended until 7 November.
Inverness Caledonian Thistle Following his release by Gillingham in May 2012, King agreed to sign for
Inverness Caledonian Thistle in July 2012. He made his debut for the side on the opening day of the
2012–13 Premier League season in 2–2 draw against
St Mirren. King was forced to retire from professional football after failing to recover from an injury sustained playing for Inverness.
Thurrock King signed for
Isthmian League Division One North club
Thurrock on 23 August 2013, reuniting with
Mark Stimson, his former manager at Gillingham. == International career ==