The Charlie's Angels actress, who is now based in the United States, has flown back to her home country especially to work on the show.
I Will Survive is a talent competition which seeks to discover a 'triple threat' entertainer who can sing, dance and act. It will be hosted by Packed to the Rafters actor Hugh Sheridan.
"We're absolutely thrilled to have Rachael on board. She's already fitting in really well and getting along with Jason, Stephan and Hugh," a Ten spokesperson told the Australian Daily Telegraph.
"She's flown in especially for this, so we couldn't be happier. We think she'll be great on the show."
The winner of I Will Survive will be trained alongside the Broadway cast of Priscilla, Queen of the Desert.
The prize package also includes winnings of AU $250,000 (£157,090), representation with a US talent agent, a month's accommodation in New York City and the opportunity to perform a Broadway showcase.