John Heitinga was part of the Ajax youth team before making his debut for the first team on 26 August 2001 against Feyenoord. He was part a new wave of talent that fielded the likes of homegrown stars Van der Vaart & Wesley Sneider well as Ibrahimovic.
Heitinga quickly established himself as a strong addition to the team and became first-choice player under coach Co Adriaanse and later Ronald Koeman until he suffered a serious knee injury which kept him on the sidelines for over six months. His comeback was short-lived, as he played only one game before suffering yet another injury which again sentenced him to a long period of recovery.
He made his second comeback at the start of the 2003-04 season and impressed in his first game since injury against FC Volendam from where he went on to become a first choice central defender for the remainder of the season as well as a popular figure amongst the fans. When it was announced that he would be leaving Ajax at the end of the 2007-08 season, the fans gave him a fitting send-off by displaying a mosaic of him on the stands.
He moved to Athletico Madrid at the end of the 2007/08 season for a fee of £8.8 million. His first season in Spain ended with Heitinga making 32 appearances (27 in the league), and scoring 3 goals for Atlético.
On 30 August 2009, Atlético Madrid accepted a bid from Everton valued at around €7.04million (£6.2million) for the services of Heitinga. John Heitinga was given Judas Lescott's old shirt number 5 following his move. Heitinga was not be eligible to represent Everton in the Europa League in the 2009/10 season as he has already played for Atletico Madrid in the qualifying stage of the Champoins League. At Everton, Johnny reacquainted himself with former Ajax teammate Peanuts. He made his debut for Everton on 13 September against Fulham after coming on for an injured Captain Phil. Johnny is quickly becoming a cult figure amonst Toffee's.
Having been part of Dutch international youth teams, Heitinga made his senior debut for the Netherlands on 18 February 2004 in a friendly game against the USA and made an immediate impact. Several months later, he scored his first goal from a van der Vaart free kick in a friendly against Greece. Although he did not take part in qualifying, he was later included in the squad for the Euro 2004 in Portugal since the U-21s had failed to qualify for the Euros. He started as first choice right back in the first two group stage matches but was suspended for the last match when he was sent-off for two bookable offences. After serving his suspension, he returned in the quarterfinal against Sweden as a second half substitute for Edgar Davids and converted his penalty as the Dutch won 5-4 on penalties. Unfortunately, the Dutch were eliminated by the hosts, Portugal in the semifinal.
Heitinga's development as a player suffered two dips in form in the 2004-05 and the 2005-06 seasons respectively. Despite club struggles, Heitinga never lost his spot in the national team under Marco Van Basten, who took over as Dutch national coach in the summer of 2004. By the end of 2005, had also once again become a key player in the Ajax squad. He would also be selected by Van Basten for the Dutch team of 23 players to compete in the 2006 FIFA World Cup, hosted by Germany. The Dutch side performed reasonably well at the World Cup, qualifying for the second round before being knocked out by Portugal. He was also called up to the Dutch squad for Euro 2008 in Austria & Switzerland.
Since the Euro 2008, he has been a regular in the right back position and has occasionally deputised in other defensive positions during an injury crisis. He made his 50th appearance for the Netherlands in a friendly against Paraguay on 18 November 2009.