After a spirited bowling performance led by Hasan Ali's three-wicket haul restricted England to 211, fifties from Azhar Ali and Fakhar Zaman set the chase for Pakistan which they completed in the 38th over with eight wickets in hand in Cardiff to reach the final of the ICC Champions Trophy.
Hasan Ali got his second big wicket of the match by striking the wicket of England captain Eoin Morgan at 33.
Morgan, Stokes and Buttler then come in, do what they do best, and take England to the ICC Champions Trophy 2017 final.
Preview: Having swept aside all opposition in the group stage, hosts England are expected to face a strong pace attack when they take on Pakistan in the first semi-final of the Champions Trophy cricket tournament in Cardiff on Wednesday.
Fakhar hit Mark Wood for the first six of the match in the opening over of Pakistan's innings and he and Azhar played some delightful strokes in a fluent partnership.
The two teams met last time in a One Day International (ODI) in September previous year in Cardiff - the same venue for today's match - in which Sarfraz Ahmed's 90 and Shoaib Malik's 77 runs innings led Pakistan to a 4-wicket victory in a high scoring game.
He smashed his fifty off 49 balls and the second one in a must win match.
Bairstow, brought in the team to replace out-of-form Jason Roy, hit 43 off 56 balls and he and Joe Root were looking all good before Hassan burst into the scene to send the opener back to the dressing room.
Pakistan marched into the semi-finals after recording a dramatic three-wicket victory against Sri Lanka at the same ground on Monday. One was a no result while Pakistan won the other game by chasing 304 in 2016.
Pakistan surprised many by bouncing back brilliantly from their heavy loss against India in the tournament opener to beat South Africa and Sri Lanaka enroute to the last four.
Zaman's catch brought curtains to Ali's innings and gave England their sixth jolt. England, who were 128 for two, lost their last eight wickets for just 83 runs.
Bairstow replaced Roy after the Surrey opener had managed just 51 runs in eight one-day worldwide innings so far this season.
Bairstow's luck ran out when a misjudged pull off Hasan's third ball sailed gently to Hafeez at deep square leg. Root fell when well set after an edged cut off leg-spinner Shadab Khan was well held by wicket-keeper Sarfraz. Skipper Morgan then joined Root and the duo batted with objective to bring up the hundred in 21.4 overs.
He eventually holed out to cover when deceived by Hasan's slower ball.
Akram, Mushtaq Ahmed and Aaqib Javed then rattled the English batting line-up that comprised of Graham Gooch and Ian Botham, restricting them to 227 - helping Pakistan win their first and only World Cup till date.
Ben Stokes, usually one of the most destructive batsmen in world cricket, needed 64 balls to scrape together 34 runs and he failed to muster a single boundary on a pitch Morgan described as hard to bat on.