Henin is due to make her official return to the WTA circuit, after an 18-month absence, at the Brisbane International tournament that starts on January 3 next year.
She will now play in the January 10-16 Sydney event which serves as a lead-up to the Australian Open starting in Melbourne on January 18.
"I have a lot of happy memories of Sydney and have won the title three times, so I am looking forward to returning in January as part of my preparation for the Australian Open," Henin said.
"The women's draw is very impressive and it will be great to get some tough, competitive matches at the Medibank International Sydney before heading to Melbourne."
The 27-year-old Belgian announced her retirement from top-level tennis in May 2008 after winning seven Grand Slam titles and spending a total of 117 weeks at the top of the women's rankings.
Nine of the women's top 10 will compete at the Sydney International. The only one 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.