Denmark's Wozniacki, 20, becomes the fourth top 20 ranked women's player to commit to the January 9-15 tournament along with US Open champion Kim Clijsters, Australian Samantha Stosur and Ana Ivanovic.
Wozniacki will return to the Sydney Olympic Park Tennis Centre for the third straight year as her leadup tournament to next year's opening grand slam in Melbourne, starting on January 17.
"I feel that the Sydney International is the best preparation for the Australian Open," Wozniacki said in a statement.
"All the top players will be competing there in Sydney and because of this I am confident that I'll get the matches I need."
Tournament Director Craig Watson said he expected seven of the top 10 ranked women to confirm their participation by the time entries close next week.