Beth Mooney, the player of the tournament at the Women's T20 World Cup, will link up with captain Meg Lanning at Welsh Fire for the inaugural edition of The Hundred.
The England and Wales Cricket Board announced Mooney, plus fellow Australians Ashleigh Gardner and Nicola Carey and South Africa all-rounders Marizanne Kapp and Chloe Tryon, as the latest internationals to sign up for the event.
Mooney was a pivotal figure in Australia's charge to a fifth T20 crown, scoring an unbeaten 78 in Sunday's final against India in Melbourne.
"I'm really excited to take part in the first season of The Hundred," said Mooney, who is top of the women's T20 international batting rankings. "It looks likes it is developing into a high-quality, world-class competition."
Gardner has become Birmingham Phoenix's second overseas signing, joining New Zealand's Sophie Devine.
Seam bowler Carey, another member of the triumphant Australia squad, will unite with compatriot Alyssa Healy at Northern Superchargers.
Kapp will join wife and Proteas captain Dane van Niekerk at Oval Invincibles while Tryon, another of the South Africa squad that reached the T20 World Cup semi-finals, is set for a stint at London Spirit.
Beth Barrett-Wild, the head of the Hundred women's competition, said: "It's fantastic to see five more international stars signing up to play in The Hundred this summer.
"We've now confirmed the names of 18 overseas players who will compete in the women's competition."
The Hundred is a new tournament consisting of eight city-based franchise sides, breaking away from England's traditional county system.
Teams will bat for 100 balls each, with overs lasting for 10 balls and bowlers either bowling five or 10 balls consecutively.
All eight franchises will feature both men's and women's teams, with the two competitions running side by side.