The Dutchman scored with his head in either half to send the hosts into the final automatic Champions League spot
Klaas Jan Huntelaar scored with a header in either half to claim a deserved three points for the home side, who leapfrog Gladbach into the final automatic Champions League qualifying place.
Schalke fashioned the first opening of the contest 10 minutes in through Julian Draxler’s charge down the left. He squared to Lewis Holtby at the top of the box, who immediately flashed an effort just wide.
The home side continued to look dangerous on the break, and found themselves a goal to the good after 18 minutes. Christian Fuchs was fed wide-left on the overlap, and floated in a teasing cross that was headed home by the unmarked Huntelaar.
Moments later, Holtby went close from range again when his stinging half-volley from 20 yards out flew inches from the top corner.
It was one-way traffic for the remainder of the half, as Schalke continued to find space in and around the Leverkusen backline. However, they just could not find the finishing touch to their work in the attacking third, as the half ended with the visitors hanging on for dear life.
Leverkusen fired a warning shot coming out of the interval, with Simon Rolfes calling Timo Hildebrand into action with a testing effort from distance.
Schalke did not take long to get back into their stride though, and Bernd Leno had to be alert to block a close range toepoke by Huntelaar, before Raul headed a Fuchs cross just over as the match crossed the hour mark.
The home side seemed unable to kill of the game, and were almost made to pay after Gonzalo Castro squared to an unmarked Andre Schurrle inside the area, but his attempt was completely mis-hit and sent well off target.
Leno was called into action once more to deny Schalke in the 70th minute. The Leverkusen keeper did well to thwart Raul from point blank range before batting away Huntelaar’s drive from the edge of the area, with Draxler firing the rebound over the bar.
Despite their slender advantage, the home side seemed comfortable as the match neared its conclusion, and Huntelaar rounded off his brace in the 86th minute to put any lingering concerns to rest. Jefferson Farfan manufactured an inch of space on the right byline, and floated in a cross that was nodded home coolly by the Dutch striker.
With Hoffenheim’s 2-1 comeback win away to Gladbach earlier on Saturday, Schalke now occupy third place in the Bundesliga with 53 points, and are six points behind league leaders Dortmund. Leverkusen meanwhile stay fifth with 40 points.