World No. 1 Serena Williams heads the line-up, which also includes Dinara Safina, French Open champion Svetlana Kuznetsova, Caroline Wozniacki and Elena Dementieva.
Victoria Azarenka, Jelena Jankovic, Vera Zvonareva and Agnieszka Radwanska also join a field boosted by Australia's No. 13 Samantha Stosur and Italy's Flavia Pennetta and Francesca Schiavone.
The only top-10 player missing will be world No. 6 Venus Williams, who will warm up for the first Grand Slam of the year with an exhibition match in Thailand.
France's Gael Monfils, ranked 13, leads a men's field that includes Tomas Berdych, Australia's former No. 1 Lleyton Hewitt and one-time Australian Open finalist Marcos Baghdatis.
"We are delighted with our confirmed player line-ups, in particular our women's field, which is certainly the strongest in the event's history," tournament director Craig Watson said.
"To have nine of the top 10 women in the world playing in Sydney is incredible and tennis fans would be hard-pressed to find a more impressive line-up, outside the Grand Slams, anywhere in the world."
Organisers will leave open spots in both draws for wildcards and qualifiers for the January 10-16 tournament.