The world number four and top seed Indian, playing with a taped-up ankle, lost 21-13 8-21 14-21 in a 48-minute contest against her second-seeded rival.
Saina ran away with the opening game in just 15 minutes with eight smash winners and better net-play but the momentum swung immediately after that as Asian Games gold-medallist Wang roared back into the match.
The Chinese, who finished runner-up here two years ago, clinched seven points in a row in the second game to equalise.
She was dominant in the deciding third game as well, leading 11-7, before Saina clawed her way back to make it 14-14.
But Wang went on to once again win seven points on the trot to close the issue in her favour.
Interestingly, Wang has had the better of Saina in their previous two encounters as well -- both of which incidentally happened in Malaysia.
The loss marks an end to Saina''s hundred per cent record in the finals of her senior career. She had won all 17 finals she played in before today.
The 21-year-old had made a shock first-round exit at the Indian Open Super Series last week.