Wiesberger began the final round with a three-shot lead, but Fleetwood caught up with a final-round 63 that included birdies on four of his final six holes. Wiesberger parred each of his last 11 holes in regulation, and then managed to birdie the first playoff hole to clinch the win.
Wiesberger entered the week ranked No. 43 in the world, and this marks his first European Tour win since the 2015 Open de France. It also continues a remarkable run of consistency as he has racked up eight worldwide top-5 finishes since his last missed cut at the PGA Championship in July.
"I've had a stretch of really good events the last couple months and it's really nice to have a trophy again," Wiesberger told reporters. "We have really good players out here, all up for it, playing well and throwing a lot at me. At the end of the day I'm just glad I got myself into the spot where I could play for the title."
Wiesberger and Fleetwood finished at 16-under 272, one shot ahead of Ross Fisher and Gregory Bourdy. Bubba Watson, who held the lead after an opening-round 66, shot a 2-over 74 in the final round to drop into a tie for 26th.