The South African led from the opening day of the €1.15 million event and completed 72 holes in a tournament-record 26-under-par 262 at Shanghai’s Tomson Golf Club.
His margin of victory was a new Asian Tour record and the second largest in an event sanctioned by the European Tour behind the 15-shot win posted by Tiger Woods at the 2000 US Open.
“I’ve been around for quite a while and experience has helped me having big leads,” said Els, who resumed with an eight-stroke lead after completing six holes in fading light on Sunday.
Britain’s Simon Wakefield finished runner-up on 13-under after a closing 73, with Denmark’s Thomas Bjorn a further shot back following a 72.
Thunderstorms on Sunday morning forced the leading 24 players to complete their final rounds on Monday.
Els’s victory was his 21st on the European Tour and 56th international title. The tournament was jointly sanctioned by the European and Asian tours. It was also his 10th wire-to-wire victory on the European Tour and gave him his third title of the year following wins in Dubai and Qatar.
Els tied for sixth at last week’s Johnnie Walker Classic in Beijing and his form in Shanghai vindicated his decision to make adjustments to his swing after finishing a career-worst 47th at last month’s U.S. Masters.
“I’m a little surprised it came so fast,” said Els, who earned €191,000 for the victory. But I had a clear vision of what I wanted to do and the changes made it a little easier to focus. Obviously the (second round) 62 was the key but you still have to hit the shots when it counts.”
The three-times major winner remains second in this year’s European Order of Merit with €819,000. His compatriot Retief Goosen heads the list with €946,000.
Wakefield’s second place was worth 127,500 and virtually secured his European Tour card for next year.
“It has not sunk in yet and it won’t until I get home and sit down and think about what I’ve done,” he said.
“It was not a great start bogeying eight and nine. Then I gave myself a kick up the backside and was thinking ‘you’re playing with Ernie Els and you’re not enjoying it. What’s going on?’ After that, the mood changed and I was fired up.”
New Zealand’s Eddie Lee and Frenchman Jean-Francois Lucquin tied for fourth on 10 under, with Britons Luke Donald and Stuart Little a further stroke back.
Meanwhile Tim Petrovic sank a 20-foot birdie putt on the 72nd hole and beat James Driscoll with a par on the first playoff hole to capture his first US PGA title on Sunday at the Zurich Classic.
Americans Petrovic and Driscoll each finished 72 holes at 13-under par 275 and Petrovic sank a four-foot par putt on the par-5 18th in the playoff for the victory, worth €990,000 dollars at the $5.5m event.
Petrovic was twice a PGA runner-up, at the 2002 St. Jude Classic and the 2003 Pennsylvania Classic, but came through with his wife and daughters in attendance.
Masters runner-up Chris DiMarco, a playoff loser in the past two majors, found more frustration with a 72nd-hole bogey to miss the playoff.
Petrovic became the fourth first-time US PGA winner on tour this year, joining Padraig Harrington, Peter Lonard and Joe Ogilvy.