Siem de Jong

Early career

De Jong began his football career at the Doetinchem amateur club DZC'68 and was scouted by De Graafschap, when he was 12. He grew up in Doetinchem and graduated from the same school (het Rietveld Lyceum) as Guus Hiddink, Paul Bosvelt and Klaas-Jan Huntelaar, which grants him immediate university access (he has considered studying economics). He played with De Graafschap until 2005, when he was picked up by the Ajax youth academy.

Ajax

De Jong made his first team debut coming on as a substitute on 26 September 2007 against Kozakken Boys. His Eredivisie debut was also as a substitute, away at Sparta Rotterdam, where he scored an injury-time equaliser. In 2007–08, he was one of the youngest players and the only player under age 20 to play more than 20 games. On 16 January, just before turning 19, he extended his contract with Ajax to June 2013. He picked up an injury against Willem II, missing two months. This made him miss all the games from 16 March onward, including matches against PSV, Twente and Heerenveen. He recovered from this injury in early April, returning fit for the match against De Graafschap. Although he did not start that game, he was substituted on in the 81st minute for Edgar Davids. During the beginning of the 2009–10, De Jong was often used as an impact substitute and only started in UEFA Europa League games. He eventually earned his place in the starting XI. In January, he scored the winner in the last few minutes of extra…

Netherlands under-19

De Jong made his international debut at the under-19 level in May 2007 against Czech Republic and capped six times. He played three games there, but the Netherlands did not qualify for the UEFA U-19 Championship. In the next qualifying campaign, he was more successful, playing three games and scoring in two of them. He scored in the qualifying campaign for the 2008 UEFA European Under-19 Championship once in his debut game in 83rd minute against Georgia (2–0 win). He started the second game but did not score. In the final game, against Norway, he scored in the 15th minute of an eventual 3–1 loss.

Netherlands under-21

On 12 November 2007, De Jong was called up to the Netherlands under-21 squad by Foppe de Haan for the game against Macedonia. Because of his injury in March, he missed the qualifying game against Estonia and was replaced by Jonathan de Guzmán. After recovering from his injury in April, De Haan recalled him but De Jong failed to make the final squad for the 2008 Olympics. De Jong played three more games for the under-21 team, but they failed to qualify for the 2009 European Championships. De Jong was recalled for the 2011 UEFA U21 Championship qualifiers and scored the opening goal against Liechtenstein in a 3–0 win.

Netherlands senior team

On 11 August 2010, De Jong made his debut for the senior side in its 1–1 draw with Ukraine in a friendly match, playing the first 62 minutes. Having been named in the…

Following his retirement from professional football in May 2023, De Jong transitioned into the administrative and technical side of the sport. In January 2024, he entered a specialized traineeship program at AFC Ajax alongside former teammates Daniel de Ridder, Ricardo van Rhijn, and Kelly Zeeman. The program was designed to integrate former players into the club's organizational structure, allowing them to gain experience across various departments including marketing, facilities, and technical management. In March 2024, it was confirmed that De Jong had taken on a more focused role within the technical heart of the club, providing support to technical director Jordi Cruijff. In this capacity, De Jong assists with scouting operations and serves as an internal technical manager, acting as a bridge between the board and the football staff. His responsibilities include providing technical analysis and supporting the management of the first-team squad and the Ajax Youth Academy.

De Jong was born in Aigle, Switzerland to Dutch parents who played professional volleyball in Switzerland and moved back to the Netherlands when De Jong was six.