With the odds stacked against after three losses and one no result in their previous four clashes against New Zealand, the West Indies pulled off a comprehensive victory after bowling out their opponents for 159 in 44.3 overs, which kept themselves in hunt for a berth in the final.
New Zealand, who had opted to bat second, started their run chase of 208 with a stutter, as they lost opener Frances Mackay (4), one-down Sarah McGlashan (18) and Sophie Devine (9) within 10 overs for only 47 runs.
West Indies pacer Tremanye Smartt's devastating first spell of 7-0-26-3 was the main reason behind New Zealand's poor start.
Smartt provided her side with the initial breakthroughs as she trapped Mackay leg-before wicket and then castled McGlashan with a yorker. Smartt would have also dismissed McGlashan, but for a no-ball. The 27-year old also got rid of Devine, though the batter was unlucky to be have been given leg before.
The New Zealand middle-order, which didn't have enough role to play in the tournament so far, struggled against the spin attack and things nosedived for the last edition's runners up, when they lost their in-form player, captain Suzie Bates, to be reduced to 83 for six.
Bates managed to score 30 off 44 balls with three fours, before she was caught and bowled by Trinidadian spinner Anisa Mohammed.
The White Ferns' misery could be gauged from the fact that they took 31 overs to post 100 runs on board. Rachel Priest (36), who batted at number seven, tried to make a fightback, but it was all too late.
Earlier, a late onslaught from Anisa Mohammed coupled with a solid 52-ball 49 from Stafanie Taylor, guided West Indies to 207 for nine.
Spinner Anisa Mohammed, who came into bat at number 10, was aggressive and her 31 runs in 32 balls, with four fours, propelled her side past 200. She forged a 45-run stand with Shanel Daley (37).
Incidentally, this was West Indies' highest score against New Zealand, the previous best being 136 in the 2009 World Cup.
New Zealand left-arm spinner Morna Nielsen ripped through the West Indies middle-order, as she scalped three for 27 runs.
Pace spearhead Sian Ruck struck early to dismiss openers, Natasha McLean and Kycia Knight, within ten overs of play, while Bates chipped in with two wickets, including that of power player Deandra Dottin.
The world record holder for fastest century in T20s, Dottin did not disappoint, as she wielded her bat to strike four fours and a six in her 21-ball 27, but it was the number seven batter, Daley, who steered her team past the 200 with a patient 37 off 64.