Prime Minister Anthony Albanese confirmed the holiday on Sunday.
“That’s to allow people to pay their respects for the passing of Queen Elizabeth,” he told ABC’s Insiders program.
“I spoke to all premiers and chief ministers yesterday and I’m writing to them formally this morning … they will have received their letters by now. They have all agreed that it’s appropriate that it be a one-off national public holiday.”
The Queen’s funeral in London has been confirmed for Monday, September 19.