The local hero carded a superb final round of five-under-par 67 at the Royal Thai Air Force Club to win the title by two strokes ahead of compatriot Prayad Marksaeng and Korea’s Kim Jong-duk, who shot 69 and 71 respectively.
Singapore’s number one Mardan Mamat fired a 67 to finish equal fourth with South Africa’s Craig Kamps, a further two shots back.
The fantastic win made Boonchu the eldest winner in the region at 47 years and 258 days, eclipsing the previous mark held by American Mike Cunning who won the 2003 Indian Open aged 44 years and 243 days.
“This is by far the best win in my career,” said Boonchu, who finished with a four-day total of 18-under-par 270 and pocketed US$48,450.
“It was nice to became the second Thai to win the Thailand Open back in 1992 but to become the first player to win this event twice is really special. I feel lucky.”
Starting the day two back of overnight leader Kang Wook-soon of Korea, who faltered with a 77 to finish joint eighth, Boonchu found the adrenaline flowing early in his round with birdies on his opening two holes.
He dropped a bogey on four but got back on track at the next hole with a tap-in birdie and a 20-foot birdie on seven. The sweet-swinging Boonchu surged to the top of the leaderboard after birdies on 10 and 14 and swapped a bogey and birdie at his final two holes.
“I had a good start but then had to steady myself after that bogey on four. After getting two more birdies, I felt I had a good chance of winning. I played cautiously throughout the day and knew I was in the lead after the 10th. I hit a nice approach on 18 and after that, I knew I would win,” said Boonchu.
Prayad carded a 69 and came the closest to challenging for the title as he pulled to one shot off the lead with a birdie on 14. But he failed to find the extra birdies in the closing stretch to settle for the joint runner-up spot.
Kang, who had led from the opening round after a 63, failed to find any rhythm in his game as he dropped three bogeys and a double bogey on his front nine. “I made mistakes with two tee shots which found water. I didn’t have any control with my irons today as all my approach were over the green,” said Kang.
Leading final round scores
270 – Boonchu Ruangkit (Tha) 68-66-69-67
272 – Prayad Marksaeng (Tha) 70-66-67-69, Kim Jong-duk (Kor) 69-67-65-71
274 – Mardan Mamat (Sin) 71-67-69-67, Craig Kamps (RSA) 70-68-67-69
276 – Richard Moir (Aus) 66-71-73-66, Paul Spargo (Aus) 67-70-68-71
277 – Thongchai Jaidee (Thai) 71-69-69-68, Kang Wook-soon (Kor) 63-69-68-77
278 – Thaworn Wiratchant (Tha) 66-68-75-69, Jim Johnson (USA) 70-67-70-71
279 – Edward Loar (USA) 71-69-71-68, Bryan Saltus (USA) 69-68-72-70, Adam Groom (Aus) 65-72-70-72, Harmeet Kahloon (Ind) 68-69-71-71, Thammanoon Srirot (Tha) 69-69-65-76
280 – Eiji Mizoguchi (Jpn) 70-72-71-67, Scott Taylor (USA) 71-71-69-69, Gary Rusnak (USA) 69-69-72-70, Mike Cunning (USA) 69-70-71-7