Meronk finished at 16 under par (272) to clinch the title at San Roque on Sunday, public broadcaster TVP Sport reported.
This season, the Polish golfer has also won the Australian Open and the Italian Open, the Onet Przegląd Sportowy website noted.
The victory in Spain moves him up to third on the DP World Tour.
The win has also earned Meronk a cash prize of EUR 637,500, the organisers announced.
Thanks to a successful season, the Polish golfer came close to making the Europe team for the prestigious Ryder Cup match against the United States, TVP Sport reported.
After Sunday, Meronk is also expected to move up the world rankings, where he is currently ranked at number 54.
(pm/gs)
Source: TVP Sport, Onet Przegląd Sportowy, ESPN