Buttler, pushed up to open at a sun-drenched and near sold-out Edgbaston, followed a match-winning century which completed England’s historic 5-0 one-day international whitewash of their Ashes rivals by this time hitting their fastest Twenty20 fifty.
He bettered Ravi Bopara’s 23-ball half-century, also against Australia in Hobart four years ago, by racing to his in 21 as England piled up 221-5 – their highest total in this format on home soil – before defying a lone-hand from Australia captain Aaron Finch (84) to close out a 28-run win.
Finch matched Buttler almost shot for shot, taking 27 balls for his 50, and hitting five sixes in 11 balls at one point as Moeen Ali bore the brunt – but he could not quite haul his team back from 72-5 as Adil Rashid (3-27) and then Chris Jordan (3-42) enforced home advantage.
Australia’s short white-ball trip therefore finishes without an international success as England proved their masters for a sixth time in 14 days.
Buttler (61) wasted no time vindicating his promotion to the top of the order, for only the second time in his Twenty20 international career, by bagging six fours and five sixes with his unique blend of power and improvisation.
Alex Hales was no slouch either, dropped down to No 4 here and responding with 49 from 24 balls.
Buttler and Jason Roy got England off to a superb start in an opening stand of 95 in under nine overs, after Australia had put them in.
Both then went in quick succession, Buttler caught at deep mid-wicket as he tried to pile into a short ball from leg-spin debutant Mitchell Swepson and Roy – badly dropped by Kane Richardson at long-off on 27 off Ashton Agar – skying Billy Stanlake into the leg-side ring.
Eoin Morgan promoted himself above Hales, but his wristy reverse-hit at Swepson merely found the hands of deep point.
It therefore fell to Hales to keep up the momentum, in a stand of 72 with Joe Root, which ended when the senior partner fell in bizarre circumstances – slapping a slower bouncer back to Marcus Stoinis’s first delivery of his solitary over for a one-handed return catch.
Jonny Bairstow strode out to administer two late maximums, though, and it seemed from the outset of Australia’s reply that they were up against it.
When Liam Plunkett made quick work of D’Arcy Short much depended on Glenn Maxwell. But Jordan had the perfect delivery for him, fooling the big-hitter with a slower one which invited ambition but messed with the timing and hit off-stump.
Finch could not get on strike in a powerplay which amounted to 59-2, and England’s spinners then took three more wickets – Travis Head, Alex Carey and Stoinis – for eight runs.
Finch responded mightily, in a stand of 86 with Ashton Agar, but was caught by Jordan off Rashid, and England’s supporters could breathe easily again.