Born in Vught, Koen van de Laak started to play for a local club named Zwaluw VFC in 1988 when he was six years old.
After spending six years in the youth team, he made his debut in the first squad of Den Bosch on 4 November 2000.
After playing some good seasons at Den Bosch and being top scorer several times, he opted to move to another team.
He quickly adjusted at Groningen, soon becoming a very important player and a fan favourite under the tenure of Ron Jans.
On 29 March 2012, it was revealed Van de Laak would leave Groningen at the end of the season, once his contract expired.