MOROCCO, 8 May 2016, (AFP) - The 20-year-old held an 18-foot putt on the 72nd hole to force extra holes after Spain's Nacho Elvira had also birdied the last following an excellent approach to within a couple of feet.
Elvira then looked to be in control of the first extra hole when he reached the par-five 18th in two, but Wang holed a 50-foot birdie effort and then converted from 20 feet for a winning gain when the pair replayed the hole.
Both men had finished the four rounds at five under after a day in which the lead changed numerous times over a testing Royal Golf Dar Es Salam Red Course.
Overnight leader Chris Hanson of England fell away after a double bogey at the eighth and finished in a tie for fifth, two shots off the lead.
England's Robert Rock and Clement Berardo were one shot off the pace.
"I'm so excited right now, I don't think I will sleep tonight," Wang, who was second in the Indian Open in March, told Sky Sports.
Asked about Elvira's approach to the first play-off hole, Wang added: "That shot was really fantastic and then I miss on the right so I was just trying to make a birdie with a hard chip.
"Actually I didn't think about birdie, I didn't think about anything, I just putted and it went in."
For the first time, both men's and women's European tours were staging events at the same venue and at the same time.
Spanish rookie Nuria Iturrios claimed a six-shot win to take the Lalla Meryem Cup in only her second start as a professional.
The 20-year-old from Mallorca fired a final round of seven-under-par 65 on the Blue Course in torrential rain for a total of 277, 11-under-par.
Overnight leader Florentyna Parker took second spot.
Iturrios said the concurrent staging of the Lalla Meryem Cup and Trophee Hassan II was a fantastic innovation.
"I really enjoyed playing at the same venue as my Spanish friends and colleagues on the European Tour. I had a lot of fun," she said.
Leading fourth round scores in the European Tour's Trophee Hassan II at Royal Golf Dar Es Salam, Rabat on Sunday (GBR/IRL unless stated, par 72):
283 - Jeunghun Wang (KOR) 71 68 74 70 (Won Play-off at 2nd hole), Nacho Elvira (ESP) 71 71 72 69
284 - Robert Rock 74 70 70 70, Clement Berardo (FRA) 70 73 68 73
285 - Chris Hanson 72 71 67 75, Nino Bertasio (ITA) 72 72 71 70
286 - David Dixon 73 71 67 75
287 - Jose-Filipe Lima (POR) 72 70 73 72, Kristopher Mueck (AUS) 72 70 73 72
288 - Jason Scrivener (AUS) 68 71 75 74, Joshua White 73 69 70 76, Renato Paratore (ITA) 70 76 69 73
289 - Callum Shinkwin 74 69 73 73
290 - Dean Burmester (RSA) 71 74 71 74, Matthew Nixon 75 72 70 73
291 - Adrien Saddier (FRA) 69 72 73 77, Nick Marsh 73 72 73 73, Paul Dunne 72 76 69 74, Jack Senior 72 70 75 74, Seve Benson 72 71 72 76, Johan Carlsson (SWE) 75 72 76 68