The Asian Tour star overhauled overnight leader Thongchai Jaidee, who stumbled to a 74 for third place with Singapore’s Lam Chih Bing. Thai-based Scotsman Kenny Walker shot a 68 to finish second.
Reigning Thailand Open winner Boonchu Ruangkit carded a 74 for tied fifth place alongside promising youngster Prom Meesawat and American jim Johnson.
Thaworn finished on 19-under-par 269 and carded five birdies against two bogeys in the final round. His successful title defence made him only the second player on the Thai circuit to achieve the feat.
269: Thaworn Wiratchant 64-66-69-70
270: Kenny Walker (Sco) 67-68-67-68
272: Thongchai Jaidee 65-64-69-74, Lam Chih Bing (Sin) 70-66-66-70
274: Boonchu Ruangkit 66-66-68-74, Prom Meesawat 67-68-66-73, Jim Johnson (US) 68-68-72-66
276: P. Gunasegaran (Malaysia) 68-69-70-69
277: Thammanoon Sriroj 68-70-68-71, Airil Rizman (Mas) 69-69-70-69
278: Prayad Marksaeng 68-72-68-70, Firoz Ali (Ina) 71-68-67-72