Wozniacki served for the match at 5-4 in the third set but Williams broke back and prevailed in the tiebreaker on her third match point after trailing 4-2.
Williams’ opponent in Sunday’s final will be the winner of the late match Saturday between Simona Halep and Agnieszka Radwanska.
The American has now won 10 of 11 matches against Wozniacki, including this year’s U.S. Open final and two other 2014 matches in which she recovered from a set down.
