He won his first two European Tour victories in back-to-back weeks in May past year.
The 21-year-old Wang, who took a three-stroke lead into the final round, shot a 1-under 71 and was joined in the playoff by South Africa's Jaco van Zyl (68) and Sweden's Joakim Lagergren (66).
Wang wasted little time in the sudden-death playoff, claiming a birdie on the 18th first hole as Lagergren and Van Zyl could only par.
Birdies at the first two holes kept Wang in charge, but he dropped a shot at the 14th and only a fifth bogey at the week at 17 came after he had moved back to -17 with a birdie at the 16th.
Wang's seven-under-par 65 lifted him to 15-under for the tournament, three clear of Jaco van Zyl and Nacho Elvira.
He had started the day three shots ahead of the chasing pack and held the lead until the closing holes. "I was nervous but I tried to look confident".
The win for Wang comes in just his 29th European Tour event. Just unfortunately I hit a couple of good putts that just didn't go in.
3 - Jordan Smith finished as best-placed Brit, in a tie for sixth place.
And in winning at the age of 21 years and 144 days, he becomes the youngest ever victor of the Qatar event. "I'm excited to play tomorrow", he said. I'm so happy about it and I hope I'm going to get in the Masters.
"My iron play was really good today and my putting was also good".
Wang shot to prominence in 2016 when he won in back to back weeks, first parlaying a sponsor's invitation at the Trophee Hassan tournament into victory then backing up the next week in Mauritius. "I can't complain about the second place, but there is obviously a lot of disappointment right now", he said. "I have a good chance to win". "But overall, I'm pretty happy", Elviro said. Former US Masters victor Adam Scott was the previous youngest, who was a 100 days older when he won in 2002.