Williamson never looked particularly fluent but reached 73 off 101 deliveries while Taylor made 52 off 64 deliveries.
Chasing 258, Pakistan got rolled for 74, their equal third lowest score of all time in one day worldwide cricket.
On the first ball of the next over Williamson wanted to run two on a drive to deep point but Guptill was too slow to respond and was easily run out for 45. This match proved to be lucky not only for the team but also for New Zealand fans. Eventually, Pakistan were bowled out for 74 in 27.2 overs.
Pakistan: Azhar Ali, Fakhar Zaman, Babar Azam, Mohammad Hafeez, Shoaib Malik, Sarfraz Ahmed (captain), Faheem Ashraf, Shadab Khan, Mohammad Amir, Hasan Ali, Rumman Raees. "The problem is (facing) the new ball", he lamented.
Fortunately, Pakistan avoided that humiliation as they stumbled on to a measly score of 74 but their capitulation and 183-run defeat see them 3-0 down in a forgettable series for the visitors.
The first in Wellington a week ago was by 61 runs, while the second on Wednesday in Nelson was by eight wickets.
"Fantastic performance all-round. It was a tough surface to get in on and gain momentum".
Boult rocked Pakistan with three wickets in five balls to take out the cream of their top order on his way to figures of five for 17.
He says they're "built strongly as a team, and have come a long way".
"We want to be a little bit better there".
Boult returned to end the innings and claim the Man of the Match award and his fourth five-wicket bag in ODIs. "Collective effort. Wanted to get the series done, knew we had to fight hard with only 250 on the board".
"That´s the focus. The focus is trying to win each game".