The Englishman completed his wire-to-wire win in style when he holed a 20-foot birdie putt on the last for an 18-under-par 270 winning total at the Kuala Lumpur Golf and Country Club.
Major champion Louis Oosthuizen of South Africa threatened briefly by shooting four birdies in his first seven holes but dropped shots around the turn saw his challenge fizzle as he signed for to a 68, taking joint second place with Austrian Bernd Wiesberger and Ryder Cup star Nicolas Colsaerts of Belgium in the US$2.75 million event sanctioned by the Asian Tour and European Tour.
EurAsia Cup star Anirban Lahiri of India, a three-time winner in the region, was the best placed Asian in tied 10th place after a closing 70 while Masahiro Kawamura of Japan, who won his first Asian Tour title last year, finished a further shot back.
Westwood, a winner here in 1997, reinforced his reputation as an Asian specialist after extending his career tally in Asia to 13 victories. The triumph came a week after the world number 36 finished seventh in the Masters Tournament last week.
"Yes this win has come at an important time. I've started working with a new coach and Billy Foster came back on my bag at the end of last year. I'm going back to what I've done before because it works. It is starting to work already," smiled Westwood, who turns 41 next week.
Westwood's victory and solid performances in the last two weeks has given him hope of regaining his best form which saw him become world number one several years ago.
"My game now has the potential to get close (to his game when he was world number one). But now I feel I got a short game and I'm starting to roll in a few putts. It makes a lot of difference when you can make up-and-downs to keep the momentum going," said Westwood, who won US$458,330 for his 41st career victory.
Oosthuizen, the 2010 Open Championship winner, was in the thick of action before a pair of bogeys on nine and 10 dashed his hopes. The South African took advantage of a four-hour weather delay to rally his spirits as he fired two straight birdies from the 16th hole to share second.
"I had the perfect start for trying to give Lee a chase. But the bogey on nine and 10 stopped the momentum and I knew that it was over to chase him. I finished well and I played nicely. I started awful this week but I'm happy with how I recovered after the first round (72)," said Oosthuizen, winner here in 2012.
"This is definitely a good finish for me especially with the way I started the tournament. I needed that (weather delay) because I was very upset with my bogey on 10. That stopped my momentum completely because I was four-under through seven holes."
India's rising star Lahiri turned in 33 highlighted by a hat-trick of birdies from the third hole before dropping his only shot on the 13th hole. He was proud with his top-10 result which capped an amazing Malaysian swing for the Indian, who was part of Team Asia who tied with Europe in the inaugural EurAsia Cup here three weeks ago.
"I played really good but I'm disappointed I didn't make any birdies on the back nine. All in all it has been a solid week but I can't help but feel that I left a lot out there. I've been hitting it really good. I hit 16 greens but didn't make the putts which I needed to. I gave myself a lot of opportunities but couldn't hole the birdies," said Lahiri.
"I came in this week feeling good about my game. I really wanted to contend badly. I tried a bit too hard and forced the issue. I didn't focus on what I needed to do. It got better on the weekend and it is good that I'm playing consistently," he added.
Scott Hend and Wade Ormsby shared the position as leading Australian when they tied for 18th.
Scores after round 4 of the Maybank Malaysia Open 2014 being played at the par 72, 6967 Yards Kuala Lumpur Golf and Country Club course (a- denotes amateur):
270 - Lee WESTWOOD (ENG) 65-66-71-68.
277 - Bernd WIESBERGER (AUT) 69-71-70-67, Louis OOSTHUIZEN (RSA) 72-68-69-68, Nicolas COLSAERTS (BEL) 66-69-72-70.
278 - Danny WILLETT (ENG) 70-66-72-70, Rikard KARLBERG (SWE) 72-69-67-70, Julien QUESNE (FRA) 68-69-69-72.
279 - Pablo LARRAZABAL (ESP) 74-68-70-67, Thomas PIETERS (BEL) 75-67-69-68.
280 - Anirban LAHIRI (IND) 72-72-66-70, Eduardo DE LA RIVA (ESP) 69-68-71-72, Garth MULROY (RSA) 71-68-69-72.
281 - Alvaro QUIROS (ESP) 73-69-71-68, Jbe KRUGER (RSA) 68-71-72-70, Jason KNUTZON (USA) 75-67-69-70, Masahiro KAWAMURA (JPN) 68-70-70-73, Andy SULLIVAN (ENG) 70-67-66-78.