Westwood finished at 20-under 268 total. Phillip Archer (65) and Fredrik Hed Andersson (66) were at 270.
'It's great to win again, although it looked like it might be a lot easier than I made it in the end,' Westwood said. 'I never really thought about going so long without a win. I've still been playing pretty well and I knew that winning is fickle, sometimes you just don't get across the line first.'
Westwood was leading by five shots eight holes to play, but the Englishman dropped three shots over the next five holes. Both Archer and Andersson eagled the 16th to close within one, but Westwood birdied the 16th and a par on the 18th was enough to win.
'Winning was very important. It wouldn't have felt good coming off with second or third after getting in such a good position,' Westwood said.
Westwood trailed by seven strokes after shooting par in the first round, but a change of putters helped him over the final 54 holes.