Munoz's par on the extra hole was good enough to seal the victory, as Im failed to get up and down after hitting his approach shot over the green.
The 26-year-old Colombian entered Sunday's final round at the Country Club of Jackson with the lead, and he held on while carding a 2-under 70. He drained a clutch birdie putt on No. 18 to force the playoff with Im.
Munoz becomes the second straight PGA Tour winner from South America after Chile's Joaquin Niemann won A Military Tribute at the Greenbrier last week.
Here's how the top of the leaderboard ended up:
|Place||Player||To Par||R4 Score|
|3||Byeong Hun An||-17||69|
Im posted a 6-under 66 in Round 4 to erase the four-shot deficit he faced prior to Sunday. The 21-year-old took the solo lead late on the back nine with three straight birdies on holes 14 to 16.
The PGA Tour heads to Napa, California next week for the Safeway Open. Justin Thomas, Patrick Cantlay, Phil Mickelson, and Francesco Molinari headline the field.