Born in east London to Jamaican parents, Campbell's professional debut was at the age of 18 for FA Premier League club Tottenham Hotspur in December 1992. Campbell spent nine years at Tottenham, scoring 10 goals in 255 appearances, and captaining the team to victory in the 1999 Football League Cup Final against Premier League side Leicester City. In 2001 he controversially joined Tottenham's North London rivals Arsenal, the first high profile free transfer within the Premier League under the Bosman ruling. In his five years and 195 appearances at Arsenal he won two Premier League winners medals and two FA Cup winners medals, encompassing the 2001–02 League and FA Cup double, and being part of the team that became known as The Invincibles for their undefeated 2003–04 Premier League campaign. Campbell was also part of the side that lost 2–1 to Barcelona in the 2006 UEFA Champions League Final, in which he scored the only goal for Arsenal. In August 2006 he joined Premier League side Portsmouth on a free transfer; his three years with the club included captaining them to success in the 2008 FA Cup Final against Championship side Cardiff City.
At the end of the 2008–09 season he made the surprise move of dropping down three levels of the English football pyramid to join League Two side Notts County on a free transfer, signing a five-year deal at the club where his former England manager Sven-Göran Eriksson had recently become Director of Football. Campbell left the club by mutual consent in September 2009, having played just one game for the club.
Campbell gained his first full cap for the England national football team aged 21. In May 1998 Campbell became what was then England's second-youngest captain, after Bobby Moore, aged 23 years 248 days. Campbell's first and only goal for England came in the 2002 World Cup in the opening group game against Sweden. In 2006 Campbell become the only player to have represented England in six consecutive major tournaments, playing in the 1996, 2000 and 2004 European Championships, and the 1998, 2002 and 2006 World Cups, and he has a career total of 73 England caps. He was named in the official Teams of the Tournament for the 2002 World Cup and 2004 European Championship.
Campbell's other honours in the game include being in the Professional Footballers' Association Team of the Year three times, in 1999, 2003 and 2004.