Buttler smashed 65 off 48 balls as England survived the hat-trick by Clint McKay to register a three-wicket win.
Cardiff: England levelled the one-day series with Australia on Saturday thanks to a stunning late show from big hitters Jos Buttler and Ben Stokes in the fourth match in Cardiff.
The dynamic young pair came together with their side appearing to be heading for another defeat and losing the series as well.
England needed 84 runs from just over 11 overs when Ravi Bopara was out.
But Buttler (65 not out) and Stokes (25) managed to turn the game on its head.
Durham all-rounder Stokes was out near the end but Buttler remained and hit the winning runs with a boundary off Mitchell Johnson with three balls remaining for a three wicket win.
It sets up a thrilling end to the series at Southampton on Monday.
Chasing 228 to win, fast bowler Clint McKay's stunning hat-trick at the start of the England innings had put Australia well on top.
The big Aussie fast bowler was called into their side as a late replacement -- and then left Kevin Pietersen, Jonathan Trott and Joe Root embarrassed as they limped slowly back to the pavilion.
Michael Carberry (63) and Eoin Morgan (53) led the recovery before both they and Ravi Bopara fell.
But Buttler and Stokes were waiting to become the stars of the hour.
England's bowling had blown hot and cold earlier in the day with the pace of Steven Finn and Boyd Rankin ripping apart the Aussie top order in seamer friendly early conditions.
And then slow bowler James Tredwell found his form late in the innings to take three wickets as Australia were bowled out for 227 off 48.2 overs.
But they had had their rivals on the ropes only to lack the know how or ability to tighten their grip on the match with vice-captain George Bailey saving his side from complete disaster with 87 from 91 balls.
Finn (2-43), struggling to rediscover some of his old form, did show real pace and zip with the Middlesex star removing opener Aaron Finch second ball.
Rankin (2-31), a real challenger for a place in the Ashes this winter, was even more impressive.
The 6ft 8in Irishman proved too good for the dangerous Shane Watson while young all-round hopeful Ben Stokes weighed in with the wicket of Shaun Marsh (25).
Finn returned to remove captain Michael Clarke and the Australians were trembling on 57-4 with England eager to inflict further damage and punishment.
Sadly, the lack of a real fifth front line bowler proved the downfall.
For Tredwell and Ravi Bopara were easy pickings for the Aussie middle order and leaked runs constantly enabling the tourists to build momentum.
Partnerships between Bailey and Adam Voges (30) and Bailey and Matthew Wade (36) frustrated Morgan's side and the Cardiff crowd who had sat back expecting England to go in for the kill.
Indeed, Australia looked set for a higher total until a sudden collapse, losing their last five wickets for just 18 runs.
Tredwell grabbed three late wickets to finishing with 3-53.
Unfortunately, for England's batting the see-saw took a dramatic and worrying dip from the moment Pietersen and Carberry walked out to the crease.
McKay's second over left England rocking.
Pietersen was undone by a swinging delivery which trapped him lbw. But both Trott and Root were guilty of bad shots and getting themselves out.
It was the 34th hat-trick in ODIs and fifth by an Australian.
Morgan joined Carberry, who had been watching from the opposite end as the carnage unfurled, and the pair slowly and surely repaired some of the damage.
The pair put on 104 runs for the fourth wicket until Morgan was bowled by Watson to 53.
Carberry's defiance ended when he missed a delivery from new Aussie fast bowler Nathan Coulter-Nile and was bowled.
Yet, the dramatic final twist of a roller coaster clash was left to Buttler and Stokes who conjured up the runs needed to see England scrape home in the final over.