Late De Jong strike sends Twente three clear
Twente, who drew their previous two matches, had a goal by Bryan Ruiz ruled out just before half-time but the Costa Rican finally broke through in the 61st minute after being set up by Nacer Chadli.
Dmitri Bulykin joined NEC Nijmegen's Bjoern Vleminckx at the top of the league's scoring charts when he grabbed his 19th goal of the season nine minutes later, controlling the ball with his chest before volleying home for Den Haag.
De Jong then struck when he pounced on the rebound after his initial header was saved by Gino Coutinho.
Twente have 68 points with two matches remaining, three ahead of PSV Eindhoven who visit mid-table Feyenoord on Sunday.
Ajax Amsterdam are on 64 points with a home game against struggling Excelsior Rotterdam coming up on Sunday.