Alex Hales's stunning century provided the platform for England to post the highest ever ODI total of 444 for three as they beat Pakistan by 169 runs at Trent Bridge.
Victory in this Day/Night clash on Tuesday gave England an unbeatable 3-0 lead in the five-match series after Pakistan were dismissed for 275.
England's total surpassed the previous record of 443 for nine by Sri lanka against the Netherlands at Amstelveen in 2006. It was also the highest ODI total in a match between two Test nations, topping South Africa's 439 for two against the West Indies at Johannesburg last year.
In a match of records, opener Hales's innings on his Nottinghamshire home ground was the highest ever-individual ODI score by any England batsman and together with Joe Root (85) he put on 248 for the second wicket.
Both batsmen fell in quick succession to leave England 283 for three in 38 overs.
It seemed England would fall short of a new record when Buttler played and missed at the fourth and fifth balls of the last over, from Hasan Ali with the hosts then on 339.
But the last ball of the innings saw Buttler, the standard bearer for England's dynamic approach to ODI cricket following their woeful first-round exit at last year's World Cup, thrash Hasan over extra-cover for four to the delight of a capacity crowd of more than 17,000.
Pakistan left-arm fast bowler Wahab Riaz, who twice took 'wickets' with no-balls, finished with figures of none for 110 in his maximum 10 overs.
Pakistan, top of the Test rankings but a lowly ninth in the ODI table, let through a couple of early boundaries to set the tone for a desperately shoddy fielding display.
Pakistan's reply saw Sharjeel Khan make a quickfire 58, but once the opener holed out off Chris Woakes his side's slim chance of victory disappeared with him.