KUALA LUMPUR, October 13, 2013 (AFP) - The 18-year-old, whose only previous victory on the tour was at the Navistar LPGA Classic in 2011, overcame an early blip before romping home to victory in the $2 million event.
She bogeyed the second hole, but recovered with birdies on the 10th, 11th, 12th and 16th holes before dropping a shot on the 17th to finish on 19-under 265.
"Having that feeling walking up to the 18th green, embracing the fans and just knowing you have the win under your belt. It means so much, especially here in Malaysia," said Thompson, who has gone winless for 43 tournaments since her 2011 title.
"I've worked so hard since Navistar, just working on my game, improving on my short game and just going in to try to win every tournament.
"It took a while longer than I thought (to get the second win) and to win it here with all the top players, it wasn't easy."
Thompson started the day with a three-stroke lead ahead of South Korea's Lee Il-Hee, but that was slashed to one by the seventh hole.
Lee, however, added bogeys on the ninth, 13th and 14th holes in an error-strewn round that undid her earlier good work which saw her take the lead in the first two days.
Asked what was going through her mind when her lead was cut to one, Thompson said she just stayed focused, and that getting three consecutive birdies from the 10th calmed her nerves.
"A lot of holes have water so I never took my victory for granted. I would say only by the 16th hole that I began to feel, I have got the win," the world number 21 said.
China's Feng Shanshan finished second with a 269 tally, while Lee and Norway's Suzann Pettersen were tied for third on 12-under 272.
Feng was delighted with her final round, which saw her move up from joint third to second after carding a four-under 67, which included a birdie on the final hole.
"After my win last week, my confidence is back and I'm really relaxed," said the world number eight.
"I'm off next week and will resume the tour in Japan."
Thompson's four-stroke victory was the largest winning margin in the four-year event. She was the first non-South Korean winner.
Kang Ji-Min and Choi Na-Yeon both won in previous years by one stroke, while Park In-Bee recorded a two-stroke win last year.
Thompson's victory was worth $300,000 while Feng, who won in China last week, took home $185,159. Lee and Pettersen both ended up $120,026 richer.
The Sime Darby LPGA Malaysia is the second of five tournaments in the Asian swing, with events in South Korea, Taiwan and Japan to follow.
Final results Sunday after the fourth round of the $2 million Sime Darby LPGA tournament at the Kuala Lumpur Golf and Country Club:
Top fourth round scores (Par 71)
265: Lexi Thompson (USA) 67-63-66-69
269: Feng Shanshan (CHN) 67-65-70-67
272: Suzann Pettersen (NOR) 67-68-67-70, Lee Il-Hee (KOR) 64-65-70-73
274: Amy Yang (KOR) 72-62-74-66
276: Sandra Gal (GER) 69-70-71-66, Chella Choi (KOR) 72-66-71-67, Alison Walshe (USA) 67-71-69-69, Beatriz Recari (ESP) 66-71-70-69, Karine Icher (FRA) 70-66-68-72, Stacy Lewis (USA) 69-68-70-69
277: Morgan Pressel (USA) 68-72-70-67, Michelle Wie (USA) 71-66-71-69, Park Hee-Young (KOR) 69-67-70-71
278: Choi Na Yeon (KOR) 76-68-68-66, Paula Creamer (USA) 66-67-75-70, Pornanong Phatlum (THA) 71-66-68-73, Ryu So-Yeon (KOR) 70-65-70-73, Anna Nordqvist (SWE) 68-71-65-74
279: Caroline Hedwall (SWE) 68-69-72-70, Jodi Ewart Shadoff (ENG) 66-70-69-74, Kim In-Kyung (KOR) 67-66-72-74
281: Carlota Ciganda (ESP) 71-69-71-70, Yoo Sun-Young (KOR) 70-68-71-72, Gerina Piller (USA) 70-66-71-74
282: Jessica Korda (USA) 68-70-76-68, Shin Ji-Yai (KOR) 71-66-75-70, Jane Park (USA) 69-69-73-71, Jennifer Johnson (USA) 71-70-68-73, Azahara Munoz (ESP) 72-68-69-73, Britany Lang (USA) 65-71-70-76