Radwanska's victory in the gruelling final, which lasted two hours and 45 minutes, also gave the 24-year-old world number four her 13th career title.
"After a great match, almost three hours of great tennis at a really high level, of course I'm very happy," Radwanska said after her win.
Pavlyuchenkova, who lost to Radwanska in the US Open last month as well, came back after losing the first three games and saved four set points to eventually win the opening set in the tie-breaker.
Radwanska wrested back control after breaking the third-seeded Russian early in the second set and closed out the match with a break in the 10th game of the deciding set.
"It was a very close match - tight sets, all of them - but I was just a little bit better in the important moments today," Radwanska said.
"And at the end of the third set I think I was playing a little bit more aggressively than she was, and I managed to win a couple more points in the end.
"In the third set I was just trying to fight every point and stay calm, and I'm happy I made it."
Pavlyuchenkova complained of fatigue and jet lag after playing non-stop in the lead-up to last month's US Open but was not too disappointed with the result in Korea.
"It's tough losing this match after fighting so long and coming so close," she said. "It's difficult and frustrating, but in tennis you can be up then down and you lose some and you win some. "I'm actually proud of myself. I had a great week. I showed some good tennis and it was a great final."