Set 93 to win after New Zealand scored 331 in their second innings, the West Indies raced to their victory target off just 13.2 overs before tea on the fifth and final day at Queen's Park Oval in Port of Spain.
Gayle smashed seven fours and six sixes to finish unbeaten on 80 off only 46 balls as the West Indies levelled the three-match series at 1-1.
Fellow opener Kraigg Brathwaite was 14 not out and named man of the match after scoring his maiden Test hundred in the first innings.
"It was a fantastic win. The conditions were tough for the bowlers," said West Indies captain Denesh Ramdin.
"The pitch was placid, it was one in which you had to keep working well."
With rain having already interrupted the final day and more showers forecast for the late afternoon, Gayle took no chances with the weather, attacking the New Zealand bowlers from the moment he took strike.
The Jamaican brought up his fifty off 28 deliveries - equalling the sixth fastest half-century in Tests - when he cracked a full toss off New Zealand leg spinner Ish Sodhi over the long-on rope.
Gayle continued his one-man assault on the visiting bowlers before sealing the win with another boundary offKane Williamson.
NO PARTNERSHIPS
"I thought we were pretty good for most of the Test match but that first innings, getting out for 220-odd was not good," said New Zealand captain Brendon McCullum.
"West Indies deserved to win. We were 160 for three and in a very good position then, we could have gone on to record 400, but there were no partnerships."
Gayle's explosive performance brought a quick end to a match that New Zealand briefly entertained hopes of saving after a stubborn batting display by their lower order and the prospect of more rain.
BJ Watling and Mark Craig both completed half-centuries before lunch to frustrate the West Indians after they had come together on Thursday at 212 for eight, with their team struggling to avoid an innings defeat.
Craig, playing in his second Test, top-scored with 67 while Watling was left stranded on 66 when he ran out of partners after batting for more than six hours.
The pair added 99 runs, a record partnership for the ninth wicket in a Test at Queen's Park Oval, but were given a helping hand from the West Indian slips cordon who dropped two straightforward catches from Craig off successive balls by paceman Jerome Taylor.
"Credit to West Indies for coming back after we had them on the back foot for the first two sessions of the Test," said McCullum.
"We will cop that on the chin, we were second best, but we need to make sure we come back strongly in the next Test."
The third and final Test in Barbados starts on Thursday.
"We were a bit lazy in the field. We hope we don't take it lightly against the lower order next time," Ramdin said.
"Hopefully we can get a good pitch in Barbados where batsmen can score runs and fast bowlers can take wickets."
Image: Chris Gayle
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