Swinkels made his league debut against Roda JC, 18 September 2005. The following season, Swinkels was mostly on the bench, but in the Spring, he began playing regularely. In the last round, he saved a ball on the goalline, which meant that Willem II was safe of relegation. In the new season, Swinkels began playing as centre-back instead of injured Delano Hill. Since then, Swinkels has been a regular starter.