Ben Sahar's first-half strike and a Samuel Armenteros penalty were enough to give the Tilburg outfit three points and 10th place in the final standings, despite a late Erik Bakker spot kick for the hosts.
The visitors were given the chance to double their lead early in the second half when Wiljan Pluim was bundled over in the penalty area.
Armenteros, playing his last game before returning to parent club Anderlecht, slotted home the spot kick to give Willem a comfortable lead.
Bakker pulled a late goal back from the spot, but the visitors managed to hang for a victory, although wins for Groningen and FC Twente mean that Willem were forced to settle for 10th position. body check tags ::