The Thorn averaged 88.30 as he won 12-10 to claim his second major on the seniors tour and the £10,000 prize pot.
Taylor got off to a great start as he won four of the first six legs, producing 14 and 15 darters along the way.
Thornton levelled the match by taking the next two legs and showed a glimpse of his best darts by closing out a 12-darter in style.
The Power responded by winning four of the next six legs to hold an 8-6 advantage in the race to 12.
However, as the 16-time world champion endured a dip in his average, Thornton capitalised and took six of the next eight legs to seal victory.
"To be honest, I think the last three matches have been absolutely outstanding just to show how much the seniors is coming on," Thornton told Online Darts TV. "It's been outstanding for everybody.
"That's what people are paying the money for. They want to come and see finals like that.
Looking back at the match, he added: "To be honest, I think he had me at one point. And then I thought, come on, dig deep. You pull one leg back then another one. Next thing you know, you're level pegging.
"I've had to dig deep the last couple of days. My form has not been great, I think the heat has been getting to me. But it is what it is. You've just got to try your best."
Thornton posted a 90+ average in just one of his four matches during the event, but that didn't stop him from picking up victories over Brian Dawson, Terry Jenkins and Martin Adams on his way to the final.
However, beating the 16-time world champion was the real coup for the 54-year-old, who said: "You've seen the way he plays. He's not practising? Don't kid me, he's still practising. He wants to win these, course he does. Everybody does."
Looking at his next aim, the Scot revealed he hopes to return on the professional circuit. He said: "To be honest with you, my biggest aim is to get my [tour] card back. And if I wasn't to do it, then my biggest aim is to defend these titles I've won and maybe win more.
"I've still got the hunger. I've still got the will to win. I think I've proved it the last couple of days."