The Jillaroos will face New Zealand in the inaugural World Cup Nines final after the Kiwi Ferns trounced England 33-4 in their final pool match.
Australia had already booked their spot after also routing New Zealand and the Lionesses in their first two pool matches.
The host nation made it a perfect three from three with a 30-6 victory over Papua New Guinea, who finished the tournament without a win.
Skipper Ali Brigginshaw continued her hot tournament form with the opening try against England on Saturday and it was all one-way traffic from there at Bankwest Stadium.
The Lionesses simply had no answer to the title favourites as Shakiah Tungai, Corban McGregor, Jessica Sergis and Tiana Penitani also scored.
An Isabelle Kelly try with the final play of the game ensured Australia’s women posted the biggest score of the tournament so far.
Earlier, New Zealand beat PNG 24-12 for their first win.
Winger Honey Hireme and centre Kiana Takairangi claimed doubles as New Zealand regrouped after their opening-night loss to Australia.