'It's been a long time coming,' Dyson said. 'A couple of years ago I thought it might never happen, but this year I thought it could, more so than any other year. I can't put it into words how good it feels.'
Andrew Buckle, who held the lead during the final round, closed with a 3-under 69 to take second place at 18-under-par 270. Thongchai Jaidee (68) and Ter-Chang Wang (70) shared third place at 14-under-par 274. Matthew Millar and Scott Strange were one stroke further back at minus-13.
The final round survived another two-hour weather delay. Friday's second-round action was delayed two hours due to lightning, forcing the round to be completed on Saturday. Sunday's final round also was halted for two hours due to thunder and lightning, but was able to be completed on schedule.
Dyson and Buckle shared the lead entering the round and their battle remained tight throughout the first five holes. Each man birdied the first and third to move to 17 under, which gave them a six-stroke cushion on the field.
Buckle edged in front with a birdie on the par-4 fifth. Things took a turn for the worse at the next though. The Australian, who was looking for his first European Tour win, may have buckled under the pressure.
The 23-year-old Buckle quadruple-bogeyed the par-4 sixth at Emeralda Golf & Country Club. He found thick rough off the tee, and took four more shots to reach the green. Once there, he three-putted to fall three behind Dyson.
Dyson put more distance between the two as he converted a short eagle putt on the par-5 seventh. Buckle did manage a birdie on seven, but now trailed by four.
'That 5-wood was one of the best shots I have ever hit,' said Dyson of his approach to the seventh.
After the duo parred the eighth, weather delayed the round for two hours.
Once they returned to the course, Buckle tried to fight back into the thick of things. He birdied the par-4 11th and made it two in a row as he ran in a 30-foot birdie putt on the 12th to get within two shots of Dyson.
Dyson, meanwhile, was in the midst of parring nine consecutive holes. The 28- year-old drained a 15-foot birdie try at the 17th to get to 20 under. He parred the last to seal his first European Tour win.
'I think he is one of the best up-and-coming players I have seen,' Dyson said of Buckle. 'It won't be long before he is sat here (in the winner's circle). He hits the ball like a top-10 player in the world and he is a very good putter. And mental wise I can't say enough. To make an eight and then throw a few birdies back at me, I don't know if I could do that.'
Buckle parred four straight after his birdie at the 12th. He also birdied 17 and parred 18 to finish two shots back.
'I told myself to try and make a game of it,' said Buckle. 'I was only four behind and I was hitting the ball well. If I could keep doing what I was doing and be patient and I had chances on the 14th and 15th. I'm proud of the way I came back. I could have let him run away with it.'
David Higgins and Shiv Kapur each posted rounds of 1-under 71 to end in a tie for seventh at 11-under-par 277.
Brad Kennedy and Steven O'Hara both fired 66s to jump to minus-10. They shared ninth place with Peter Gustafsson, Anders Hansen, Jose Manuel Lara, Wei Chih Lu and Terry Pilkadaris. Thaworn Wiratchant, the 2005 champion, ended in a tie for 19th at eight-under-par 280 after a final-round 70.