According to organisers, Miller is expected to arrive just before the event, which will be held on February 12 at Movies by Burswood, reports the Herald Sun. They say the British actress has not asked for a fee.
"She's just doing it as a nice gesture,'' said Grant Thomas, one of the partners with event organisers I-Spy. "She thought it would be a nice thing to do for Heath and his family," Thomas said.
According to Thomas, they have been planning the night for more than a year and have the support of the Ledger family. Former supermodel Gemma Ward, who was romantically linked to the late actor, is also set to fly in for the night. Both Miller and Ward are expected to mix with VIP guests.
More than 1,200 people are expected to attend, with money raised going to Telethon, His Majesty's Theatre Foundation and the Australians in LA Foundation, which supports upcoming actors in Hollywood.