Sindhu, fresh from capturing the China Open in Fuzhou last week, looked hesitant as she struggled to match the pace of the Taiwanese player, who unleashed a mix of well-timed lobs and drop shots in her 21-15, 21-17 victory.
"It was a good game overall, but it was her day," said Sindhu, who downplayed suggestions her win at Fuzhou had left her drained in Hong Kong. "I'll go back and train hard."
Tai cruised through the first game with relative ease, remaining cool as she controlled the contest's tempo and placement of the shuttlecock.
Sindhu rallied in the second but was unable to establish a rhythm as Tai pulled away in the latter half of the game.
The 22-year-old was patient during longer rallies, with her opponent struggling to reach shots and keep the shuttlecock in play.
"I like to be easy during my matches. I don't like to put too much pressure on myself," said Tai, who booked her ticket to the final a day earlier by beating Rio gold medallist Carolina Marin.
Tai's triumph in the Hong Kong Open marked her second superseries win of the season after clinching the Indonesia Open title in June.
She said her eyes were now firmly set on finishing the season on top at the tour final in Dubai, a tournament she won in 2014.
On the men's side, Hong Kong's Angus Ng nabbed his first superseries title after battling through a tough three-game scrap with India's Sameer Verma in front of a packed house.
The hometown favourite put on an aggressive display early with repeated whipping overheads and down-the-line winners, chalking up a 21-14 win in the first game.
But the 43rd ranked Verma fought back with the relentless hustle of an underdog with nothing to lose in the second, as Ng appeared to falter under the pressure.
The 14th ranked Ng later regained composure in the third as his opponent struggled with unforced errors and lengthy rallies at the net that saw Verma grow visibly frustrated.
"In the third game I just forgot about what happened in the second," Ng told reporters after the 21-14, 10-21, 21-11 win.
The Hong Kong native rounded out his maiden superseries victory by uncorking leaping overheads coupled with dropshots, falling to his knees to celebrate after Verma whiffed the match point as thousands roared in approval.
"When I was younger I wished I could play in the finals of the Hong Kong Open in the future," said the 22-year-old Ng.
Verma, a relative unknown in the badminton world stayed humble following his improbable run.
"I was a little bit nervous," said Verma. "I didn't expect to reach the finals."
Winner Tai Tzu-ying of Taiwan (R) poses with second-placed P.V. Sindhu of India after the women's singles final at the Hong Kong Open badminton tournament in Hong Kong
World number three Tai Tzu-ying won the women's singles at the Hong Kong Open Sunday, dashing P.V. Sindhu's hopes of back-to-back superseries titles and avenging her loss to the Olympic silver medallist in Rio.
