The Thai star, untouchable at the top of the leader board since the second round, carded a two-under-par 70 to win by two strokes from India's [ Images ] Gaurav Ghei.
Ghei celebrated his 37 th birthday by closing with a superb 66.
Thailand's Prom Meesawat finished joint-third place for his best finish on the Asian Tour, after shooting a 70, along with South African Hendrik Buhrmann.
"I just made less mistakes this week. It's a very tight track but I only missed four fairways all week. I played really carefully, very often using an iron off the tee," said Thaworn, who also won the Indonesian and Taiwan Opens this season.
Thaworn cemented his lead on the Asian Tour Order of Merit with his winnings of US $47,250 taking his season earnings to US$448,225. He now leads second place Thongchai Jaidee from Thailand by US $94,505.
"I don't know why I am playing so good this year. I have been doing the same thing throughout my career right from when I was an amateur. I think I am just more lucky now," added Thaworn. He finished the tournament on 16-under-par 272.
He made four birdies and two bogeys.
Ghei produced his best finish in his national Open thanks to holing a bunker shot for a birdie on the par five 18th. He squandered three birdie putts in a row on the back nine. He missed from three feet on 14, five feet on 15 and 12 feet on 16.
"It was a dream round. I told my caddie in the morning if we get to 15 under we might have a chance. I played my heart out," said the Indian.
Meesawat was delighted with his performance.
"This is great. Last year I was worried about making cuts now I don't even think about that. I am playing really good right now. Always thought I had a chance to win," said Meesawat, who was disappointed to bogey nine and 10, the two holes in birdies in the third round. Buhrmann also came in with a 70.
Australia's [ Images ] Terry Pilkadaris finished in outright fifth place.
India's Arjun Atwal [ Images ] closed with a 70 to finish the tournament on seven under par in joint 11th place. Defending champion Mardan Mamat from Singapore shot a 72 to end on level par.
Leading final round scores:
272 - Thaworn Wiratchant (THA) 68-66-68-70
274 - Gaurav Ghei (IND) 67-72-69-66
275 - Hendrik Buhrmann (RSA) 66-70-69-70, Prom Meesawat (THA) 69-67-69-70
278 - Terry Pilkadaris (AUS) 67-70-70-71
279 - Mukesh Kumar (IND) 71-69-71-68, Jyoti Randhawa (IND) 69-70-67-73
280 - Ashok Kumar (IND) 69-71-72-68, Rick Gibson (CAN) 73-65-73-69, Shiv Kapur (IND) 70-69-72-69
281 - Arjun Atwal (IND) 70-68-73-70, Shamim Khan (IND) 71-68-71-71, Scott Taylor (USA) 71-67-72-71, Jaiveer Virk (IND) 68-71-68-74
282 - Jochen Lupprian (GER) 70-72-71-69, Gary Simpson (AUS) 68-69-73-72, James Kingston [ Images ] (RSA) 76-66-68-72, Bryan Saltus (USA) 68-70-70-74, Digvijay Singh [ Images ] (IND) 66-70-72-74, Harmeet Kahlon (IND) 71-64-73-74.