Poulter, the Ryder Cup star for Europe's winning team this year, won by two strokes. He finished at 21-under 267 on the Olazabal Course at Mission Hill Golf Club.
It was the Englishman's second World Golf Championship victory — he also captured the Accenture Match Play Championship in 2010. This was his first title of any kind since the Volvo World Match Play Championship in May 2011.
Phil Mickelson (68), Jason Dufner (64), Scott Piercy (65) and Ernie Els (67) tied for second at 269. Lee Westwood (72) and Louis Oosthuizen (72) were another shot behind at 270.