Meronk -- who already has three top-three finishes this season -- shot a final-round 66 to top the leaderboard at 20-under and become the first Polish winner in European Tour history.
"It means a lot," Meronk said. "As I said before, it's one of my roles to just grow the game in Poland because it's still quite small but hopefully this will help a lot so I'll just keep going and, yeah, hopefully there will be a lot of new people to the game in Poland."
Fox shot his second 64 of the event to finish three shots back at 17-under, while South African Thriston Lawrence was another shot back at 16-under.
Defending champion Lucas Herbert finished at 12-under.