Ajax On 19 October 2002, De Jong made his debut for the Ajax first team. He scored his first goal of his senior career on 18 February 2003 in a 1–1 draw against Arsenal in the Champions League. He became a first team regular the following season, in which Ajax won the Eredivisie title. In 2004–05, his last full season in Amsterdam, De Jong was named Ajax Player of the Season. which was due to end in July 2006.
Hamburg On 26 January 2006, De Jong signed a four-and-a-half-year contract at
Bundesliga club Hamburg, the transfer fee approximately €1 million. At Hamburg he joined two other Dutchmen:
Rafael van der Vaart and
Khalid Boulahrouz. He made his Hamburg debut two days later in a 2–1 defeat at
Nürnberg. In March 2006, De Jong scored the winning goal in
Bayern Munich's first ever defeat at the
Allianz Arena. The following week he received the first red card of his career for a second booking in a
UEFA Cup match against
Rapid București. His season was cut short in April, when he required surgery on a knee problem. The injury also kept him out of the Dutch squad for the 2006 World Cup, though he was later put on standby after regaining fitness.
Manchester City On 21 January 2009, De Jong was signed to Manchester City for an estimated fee of £18 million and was assigned the number 34 shirt. He made his debut for the club against
Newcastle United on 28 January 2009. He made sixteen appearances in the
Premier League over the second half of the season. De Jong was given a start against
Arsenal on 12 September 2009. He was named Man of the Match by Sky Sports in a 2–1 win over
Chelsea on 5 December 2009. By the end of the season he had become a firm fans' favourite as well as being one of new manager
Roberto Mancini's first picks as defensive midfielder as the team narrowly missed out on a Champions League berth. De Jong scored his first goal for Manchester City in a 2–1 victory against West Ham United on 1 May 2011. De Jong was a member of the City side which won the
2010–11 FA Cup and the
2011–12 Premier League, making 137 appearances and scoring twice before being sold to
A.C. Milan in August 2012.
AC Milan On 31 August 2012, De Jong joined Italian club
AC Milan for £3.5 million rising to £5 million depending on appearances, signing a three-year deal. On 1 September, De Jong made his debut against
Bologna. De Jong scored his first goal for Milan in a 3–2 loss against
Lazio on 20 October. On 4 May 2014, De Jong scored his second goal for Milan, the winning goal against
Inter Milan in the
Derby della Madonnina at the
San Siro. On 26 June 2015, Milan announced De Jong had signed a contract extension to keep him at the club until 2018.
LA Galaxy On 31 January 2016, it was reported that De Jong had negotiated to terminate his contract with Milan and joined LA Galaxy on a free transfer, signing a one-year deal. He was involved in a controversial incident in a game against the
Portland Timbers on 10 April when his strong tackle left
Darlington Nagbe injured and in need of treatment. De Jong was only shown a yellow card by referee
Allen Chapman, but was later suspended for three games. He received a red-card after a bad tackle on
Blas Perez on 5 July; although a man down, the Galaxy were still able to hold on for the win over
Vancouver Whitecaps FC. On 29 August 2016, the Galaxy announced that they and the Dutch midfielder mutually agreed to terminate de Jong's contract, freeing the 31-year-old to sign with Turkey's
Galatasaray. De Jong reportedly would have been tagged as a Designated Player for the upcoming 2017 season. He appeared in 18 regular season contests for Los Angeles, failing to record a goal or an assist in regular season play but establishing himself as a starting presence as a defensive midfielder.
Later career On 31 August 2016, De Jong signed for Turkish outfit
Galatasaray on a two-year deal. On 5 January 2018, De Jong's contract was terminated by Galatasaray. On the same day, he agreed a free transfer to
Bundesliga side
Mainz 05. In July 2018, De Jong moved to Qatari club
Al Ahli. A year later, he moved to
Al-Shahania in the same league. ==International career==