The sixth-ranked Wozniacki, a finalist in 2010, leads the tour with most match wins in the season at 59-21 as the Dane heads into Sunday’s championship match.
The third-ranked Pliskova’s loss is good news for Simona Halep, who will retain the No. 1 ranking through to next year.
Pliskova, playing in the year-end semifinals for the first time, needed to win the WTA Finals title to return to the No. 1 ranking for a second time this year.
Wozniacki improved her career record over Pliskova to 6-3, and is 3-2 in meetings this year.
Both players had six set points in the first set, but it was Wozniacki who capitalized on the sixth offering when Pliskova netted a backhand.
All six of Wozniacki’s set points were in the tiebreaker where she initially led 6-1. Pliskova had her first three set points on Wozniacki’s serve in the 10th game and three in the tiebreaker.
From 3-3 in the second set, Wozniacki won 12 of the last 15 points to take her place in the final.
Hingis and Chan won nine titles this season, including the U.S. Open trophy.
“I think it’s been an amazing journey and amazing career that I can be proud of,” said 37-year-old Hingis, who announced Thursday she was retiring at the end of the tournament. “It’s not really goodbye. I hope I’ll still be part of the game.”