DONGGUAN, China, Nov 4, 2012 (AFP) - The Englishman started the last round four off the pace but he crafted eight birdies against a lone bogey -- on the penultimate hole -- before sealing a nerve-jangling, two-stroke win with a ice-cool par putt on the 18th.
Poulter fired rounds of 69, 68, 65 and 65 for a total score of 21-under-par 267, with Phil Mickelson, Ernie Els, Jason Dufner and Scott Piercy sharing second place on a congested leaderboard.
Overnight leaders Louis Oosthuizen and Lee Westwood faltered to finish a shot further back with Adam Scott eighth, defending champion Martin Kaymer ninth and Bill Haas 10th on the par-72 Olazabal Course.
Poulter claimed the $1.2 million winner's cheque with his first individual win of the season, and the 15th of his career -- just a month after playing a key role in Europe's come-from-behind Ryder Cup triumph at Medinah.
"After the Ryder Cup I came here in good spirits. I played well last week and took a lot that I knew that if I did the right things this week and stayed patient I'd be right there at the end. It's just so nice to get another win," he said.
"It was a special day... I knew there was a good round of golf in me on this course."
Westwood and Oosthuizen started the day with a handy three-shot advantage over the chasing pack, but the South African's bogey on the very first hole was the cue for a spell of dramatic upheaval on the leaderboard.
Westwood gave up a two-shot lead when he double-bogeyed the fifth, but then inched back in front with a long birdie putt on the par-three eighth.
But Poulter and Mickelson were making a charge and when Westwood made bogey on 10, they joined the Englishman and Oosthuizen in a four-way tie for the lead at 19-under-par.
With half the round to play, 10 players were within three shots of each other at the top of the board, making it anyone's guess who would emerge with the Old Tom Morris Cup.
Poulter, turning in 32, leapt ahead with consecutive birdies on 10 and 11, and another on 14 gave him a two-shot cushion ahead of Mickelson and Kaymer, who put together five birdies in six holes after the halfway point.
Poulter looked in trouble when he bunkered his second shot greenside on the spectacular, par-five 15th, but he flopped out to 15 feet and then steadied himself to grittily hole it and extend his lead to three shots.
Westwood and Kaymer's assaults were over when they both thinned chips across different greens within minutes of each other, for bogey and double-bogey respectively.
Poulter looked home and dry, but a "disastrous" chip left him with a long par putt on the 17th and he just failed to down it, cutting his lead to one shot from Mickelson, who had two holes left to play.
And there was more drama when Poulter put his second shot on 18 into a bunker -- but he chipped out to five feet and, in front of massed galleries at the Dongguan clubhouse, held his nerve to down the putt and make sure of the win.
"I feel confident when I'm in good form and I've been in good form for a little while," Poulter said. "It's just so nice to get my hands on another trophy."