AUSTRIA, 12 Jun, 2016, (AFP) - Wu, 30, who became the first Chinese player to win on home soil on the European Tour when he captured the 2015 China Open, started the day a shot off South Africa's Zander Lombard at the top of the leaderboard.
He took victory after a closing 69 to finish the week on 13 under.
Spain's Adrian Otaegui finished second on 12 under, with Englishman Richard McEvoy another stroke back after dropping his only shot of the day at the 18th.
England's James Morrison was fourth and Lombard finished fifth.
"I am very happy right now. It was a very exciting finish and I still cannot believe it, but my playing partners were really good today and the scores were very close," said Wu, who slipped into second place when McEvoy birdied the 13th.
A matching birdie at the 13th moved Wu back into a share of the lead before another gain two holes later saw him stand alone at the top of the leaderboard.
Otaegui fired a birdie at the 16th to join Wu at the top of the pile but the Spaniard dropped a shot at the next and pars at the final three holes were enough for Wu to secure the trophy.
"At the 10th and 11th holes I just played two bad shots. I still kept working after that to do my best to make birdies and I did that," said the Chinese.
"I just kept focused over the last putt and I talked to my caddie and he said, 'It’s no problem, it’s an easy line so just putt it in the hole.'"
Leading final-round scores in the Austrian Open at the Diamond Country Club in Atzenbrugg, Austria on Sunday (GBR/IRL unless stated, par 72):
275 - Wu Ashun (CHN) 69-72-65-69
276 - Adrian Otaegui (ESP) 64-76-67-69
277 - Richard McEvoy 71-69-68-69
278 - James Morrison 70-72-68-68
279 - Zander Lombard (RSA) 67-70-68-74
280 - Chris Wood 71-71-70-68, Joost Luiten (NED) 69-71-68-72, Gregory Bourdy (FRA) 68-69-70-73, Gary Stal (FRA) 67-71-76-66
282 - Magnus A Carlsson (SWE) 71-74-67-70, Robert Dinwiddie 73-73-68-68, Richard T Lee (CAN) 71-76-66-69, Chris Paisley 71-73-66-72, Nick Cullen (AUS) 71-73-68-70, Tjaart Van Der Walt (RSA) 72-74-68-68, Chris Hanson 71-74-67-70, Eduardo De La Riva (ESP) 69-74-68-71, Bernd Wiesberger (AUT) 70-74-69-69
284 Ricardo Gouveia (POR) 69-74-68-73, Steve Webster 71-73-69-71, Mark Foster 74-72-67-71, Matthew Southgate 70-76-71-67, Nino Bertasio (ITA) 72-74-68-70