Mooney cracked a superb unbeaten 94 from 63 balls as Australia posted 5-162 at Adelaide Oval on Saturday night.
England were bowled out for 90 in 17.3 overs, with Georgie Wareham taking 3-11 as Australia swept the three-match T20 series.
The Australians also logged a 3-0 win in the preceding best-of-three 50-over series.
Australia can seal the perfect Ashes with victory in the one-off Test match at the MCG starting Thursday.
Vol(l) is French for 'flight' 😌— cricket.com.au (@cricketcomau) #Ashes pic.twitter.com/vZNOOl48UXJanuary 25, 2025
Mooney, before a crowd of 10,921 - a record for an Australian women's white-ball international in Adelaide - fell just shy of becoming the first Australian to score three T20 international centuries.
Mooney has two T20 international tons, as does retired great Meg Lanning.
But she extended her torment of the tourists, following scores of 44 and 75 in the initial T20 encounters.
Mooney laced her 25th T20 international half-century with 10 fours, including an audacious ramp shot from pace bowler Lauren Filer.
The 31-year-old set the tone with opening partner Georgia Voll (23 from 21 balls), the pair making a half-century partnership from 41 balls.
The stand ended on 56 when Voll was caught at deep wide mid-on but Mooney continued on her merry way despite the frequent loss of partners.
Phoebe Litchfield (12 from 10 balls), Ellyse Perry (12 from 11 balls), Grace Harris (11 from 10) and Annabel Sutherland (three from three) fell cheaply.
England's run chase started poorly - they were 3-23 in the fourth over.
Darcie Brown (Left) has taken two wickets in Australia's T20 win over England in Adelaide. (Matt Turner/AAP PHOTOS)
And the fate of the tourists was effectively sealed when spinner Wareham took two wickets in three balls in the seventh over as England crashed to 5-39.
Darcie Brown (2-25) struck again in the next over and Wareham claimed her third victim just three balls later as the Poms slumped to 7-48.
Alana King (1-17), Annabel Sutherland (1-14), Tahlia McGrath (1-4) and Megan Schutt (1-17) were also among the wickets.
Only two English batters reached double-figures with captain Heather Knight top-scoring with 40 from 38 balls.
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