In at first drop, a defiant Sophia Dunkley (59 from 30 balls) hit the highest score of any England batter this series to single-handedly keep the tourists in the game.
But England were still 89 runs short of their target when stand-in captain Tahlia McGrath collected Dunkley’s leg stump in the 12th over and put Australia back on the path to victory.
England were all out for 141 in the 16th over and need to win the remaining two T20Is and Test match to level the series.
“We’re obviously very disappointed,” Dunkley said.
“We came here with a really open mindset of a new format, fresh format, and we just couldn’t put them under pressure for long enough today. We’ve come away falling short.”
Having won the three One Day Internationals, reigning Ashes champions Australia now cannot be overtaken on points aggregate.
Win or draw any of the last three matches and Australia will claim a series victory, but the availabilities of captain Healy (foot) and star allrounder Gardner (calf) are under a cloud.
Both were ruled out ahead of the toss, with Healy experiencing soreness in the same foot she injured at last year’s T20 World Cup and Gardner diagnosed with a low-grade calf strain.
Having played the steady hand alongside debutant Georgia Voll (21) early on, Mooney cut loose after drinks for a 23rd T20I half-century, and ultimately her third-highest T20I score.
She was given lives on 16 and 23 runs, first dropped by wicketkeeper Amy Jones and a chance was then allowed to bounce at cover as Nat Sciver-Brunt and Charlie Dean miscommunicated.
England tightened their act up in the field after drinks to get back in the game, with captain Heather Knight running out Phoebe Litchfield (25) with a direct hit from 20 metres.
The tourists would’ve felt right in the game at 4-121 when allrounder Annabel Sutherland (3) holed out to mid-wicket, but Mooney clicked into gear, with quick Lauren Bell a favourite victim.
Mooney slapped Bell for three fours - all behind the wicket - in the space of four balls in the 16th over before Jones eventually stumped her from Freya Kemp’s bowling in the 18th.
England’s run chase could hardly have started worse, with Maia Bouchier picking out Georgia Wareham in the deep on the second delivery of the innings from Megan Schutt (1-35).
AAP