McIlroy won his first professional career title in the competition in 2009 and his two-under-par final round was enough to hold off a battling Meronk and overtake Ernie Els for the most wins at the event.
"It's really cool," McIlroy said. "I didn't really think about that during the course of the round, it was a really tricky day."
McIlroy began the day alongside Meronk, two shots off American Cameron Young, and the world number two completed his comeback after Friday's third round saw him come from 10 shots behind to within striking distance of the leader.
Young hit two bogeys on the front nine and McIlroy took full advantage to take a three-shot lead at the turn, while Meronk looked out of the running with a double-bogey on the seventh and a bogey on the ninth leaving him five shots behind.
Meronk recovered and got to within one shot of the leader by the 14th with three birdies in the first five holes of the back nine as McIlroy hit his first bogey of the round at the 13th, but Meronk's bogey on the 16th restored the gap.
The Pole hit a birdie at the last to take him back to one-shot behind and put some pressure on McIlroy, but the Northern Irishman showed his experience to par the final hole for the win.
"It's a great start to the season, last year I started well with a win here, it's a great platform to build from," McIlroy said.
Young, who had taken the lead after the second round, had to settle for third place, finishing on 12-under-par overall.
