After restricting Ireland to a paltry 91 for seven in 20 overs, the 'Southern Stars' raced to the target in only 13.2 overs to finish the match in style.
The defending champions thus finished with six points from four league games and will have to wait for New Zealand's game against South Africa to know their qualification status.
If the New Zealand women win, the Southern Stars will be through to last four stage.
The Irish women could never really get going as the Aussie bowlers maintained a disciplined off and middle stump line.
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In reply, Australian team were always in command despite losing Alyssa Healy (6) early in the innings due to a mistimed pull-shot off Ciara Metcalfe.
Skipper Meg Lanning (8) was also out cheaply but Elyse Villani (43) and all-rounder Ellyse Perry (29) added 54 runs together for the third wicket to seal the issue with 40 balls to spare.
Brief Scores:
Ireland Wom: 91/7 in 20 overs (Clare Shillington 23, Kim Garth 27, Megan Schutt 3/29).
Australia Wom 92/3 in 13.2 overs (Elyse Villani 43, Ellyse Perry 29 no). Australian women won by 7 wickets.