New Zealand-born all-rounder Ben Stokes has guided England to Cricket World Cup glory, beating the Blackcaps in a dramatic thriller in the final at Lord's.
After the Blackcaps posted 241/8 in their 50 overs, Stokes hit an unbeaten 84, as England reached 241 to force the match into a 'super over'.
Stokes (eight) and Jos Buttler (seven) then posted 15 runs in the extra six balls, which New Zealand matched, but as England had a superior boundary count, they were crowned men's world champions for the first time.
The pair were also responsible for getting England back in the contest during the chase, coming together at 86/4 - but their 110-run partnership (Buttler 59, Stokes 82no) put them in the driving seat.
After losing in the World Cup final four years ago to Australia in Melbourne, Williamson's side were determined to come out on top and remove the underdog tag, which has long been associated with his team.
But on a green pitch, lots of marginal calls went the hosts' way - especially in the final over - but ultimately, they proved too strong in front of a vocal crowd.
England needed 22 to win with nine balls remaining and two crucial plays put the hosts in the box seat. Stokes hit one ball for six, after Trent Boult stood on the boundary rope trying to get a catch.
A few balls later, Martin Guptill threw the ball towards the stumps, and it hit Stokes' bat and rolled to the boundary for four, and they claimed a further two runs for running between the wickets.
Boult then came up huge off the final two balls to force the match into the super over.
New Zealand needed two runs off the final ball in the super over, with Martin Guptill facing strike, but he was run out attempting to claim the game-clinching run.
In the end, the match was decided on a countback of boundaries, with decided by England's superior count.
The result comes 12 days after England crushed New Zealand by 119 runs during the round-robin stages of the tournament at Durham.
The Blackcaps nearly got off to a horrible start, as Nicholls was given out lbw on 0, before ball-tracking showed the ball was going over the stumps.
Guptill (19) was the first batsman dismissed in the seventh over, as Chris Woakes (3/37) rapped the dangerous opener on the back pad to have him leg before wicket.
The opening batsman reviewed the dismissal, only for it to be upheld, and that decision would come back to hurt the Blackcaps later in the innings.
Williamson (30) joined Nicholls at the crease and the pair put on a 74-run partnership, before the Kiwi skipper was caught behind. He was initially given not out on the field, before the third umpire overturned the decision.
Nicholls was the victim, when he inside-edged Liam Plunkett's (3/42) delivery onto the stumps.
In the 34th over, the wasted review came back to bite New Zealand, when Ross Taylor (15) was given out by a ball from Mark Wood (1/49), as he tried to steer it around his front leg. Replays showed the ball would have gone over the top of middle stump.
From there, Tom Latham (47) did his best to steer New Zealand to a modest total, before Woakes dismissed both he and Colin de Grandhomme (16).
New Zealand eventually reached 241/8, which untimely proved not enough.
The Blackcaps nearly got off to the perfect start with the ball, when Jason Roy (17) survived an lbw from Trent Boult (0/37) off the first delivery of the game. Roy was dismissed in the sixth over by Matt Henry (1/40).
De Grandhomme (1/25) then got the wicket of Joe Root, as the Blackcaps all-rounder bowled the economical 10-over spell in a World Cup final since Derek Pringle's 3/22 in 1992.
Jonny Bairstow and Eoin Morgan then fell in quick succession, which saw England at 86/4 near the halfway stage.
But Buttler and Stokes' partnership helped put England in the box seat, as the match came down to the wire.
Lockie Ferguson (3/50) claimed the wicket of Buttler and then Chris Woakes, before Jimmy Neesham (3/43) got Liam Plunkett (10) and Jofra Archer (zero), as the match went down to the final over.
Eventually, England needed three off the final two balls to win, but could only manage two to send the match into the super over.
But the rub of the green was once again on England's side, as Jofra Archer delivered the goods with the ball to prevent New Zealand from winning.
Neesham did his best to put the Blackcaps in a winning position in the super over and it was down Guptill to hit the winning runs, but he only managed one.
It meant England were crowned world champions by virtue of having scored more boundary fours and sixes - 26 to New Zealand's 17 - in the entire match.
In a cruel twist, Stokes was named Player of the Match.