Westwood finished the tournament comfortably with a 22-under total of 266 for his fourth title of the year.
Lee Westwood says Thailand title was his to lose
Lee Westwood of England completed a comprehensive victory in the Thailand Golf Championship yesterday, shooting a three-under 69 to beat his nearest rival, Charl Schwartzel of South Africa, by seven shots at the Amata Spring Country Club.
Westwood finished the tournament with a 22-under total of 266 for his fourth title of the year.
"It means a lot, any win does," Westwood said. "It's special this week because of the difficulty of the golf course, who I was up against in the weekend.
"Charl is the Masters champion and he has had a great year. The fact that I led wire to wire - 60 in the first round and 64 in the second round, 20 under after two rounds - it's yours to lose, really, with an 11-shot lead. There was pressured involved."
Although he never caught Westwood at the top of the leader board, Schwartzel closed to within two after he eagled the 11th and birdied the next when he sank a 30-foot putt.
That was as close as Schwartzel would get as Westwood also birdied the 12th to extend his lead to three before stretching the gap with birdies on holes 13 and 15.
"It was a tough day. The wind probably blew the hardest today compared to the last three rounds," Schwartzel said. "I played great. If it wasn't for Lee, I would have probably won the tournament."
Elsewhere, England's Ian Poulter won the Australian Masters, spoiling Geoff Ogilvy's bid for a victory on his hometown course. Poulter, two strokes behind Ogilvy entering the final round, closed with a four-under 67 in windy conditions to finish at 15-under 269 at Victoria Golf Club.
"To come down here the week before Christmas and to win this tournament is very special," Poulter said.
Top-ranked Luke Donald, who won the European and American money lists this year, had a 72 to tie for 12th at four-under.