James Vince top-scored for the new-look England side as he slammed 59 off 38 balls to muscle his side's chase of the modest 154-run target.
England's innings faced no hiccups along the way with Vince's immaculate strokes steadily driving them towards a comfortable victory.
Although Mitchell Santner strove to make inroads into the England batting with an extraordinary spell of 3-23, the tourists nullified the challenge posed by other bowlers to clinch the first game of the five-match series.
Skipper Eoin Morgan batted maturely to seal the chase without further loss after the departure of Vince in the latter stages of the game.
Morgan finished with an unbeaten 34 off 21 deliveries with his newly appointed deputy Sam Billings hitting two fours during his 11-ball stay at the crease.
England had fielded a horde of youngsters including the three debutants - Sam Curran, Pat Brown and Lewis Gregory - in today's match.
The decision to leave out senior players such as Ben Stokes, Jos Buttler, Moeen Ali and Jofra Archer for the short-form games is interpreted as a way to afford them rest following an exhaustive period of cricket.
While Gregory failed to get a chance to showcase his batting or bowling skills, Curran and Brown claimed a wicket each to impress their captain.
"The game was won and lost in the first innings... James Vince played outstanding well but all credit to the bowlers today," Morgan said, praising his bowlers for restricting the hosts to 153 for five in their 20 overs.
"It's a chance for them to stake their claim," he added in a coaxing manner.
Morgan, who scored England's winning runs in style by a mighty heave over midwicket for six, stressed the need for increasing the bench strength as part of the preparations for the T20 World Cup next year in Australia.
New Zealand were without their best player in the side Kane Williamson, who was ruled out of the series owing to a hip injury.
In his absence, stand-in skipper Tim Southee admitted they were bereft of the batting prowess and tactical acumen to succeed in the contest.
"We were probably a little bit off in all three areas," he said.
"We got a score on the board that we felt we could defend but we were a little bit off with the ball and in the field, which didn't help."
Martin Guptill's torrid form witnessed during the World Cup continued as he was outfoxed by Curran's in-dipper that took the inside edge and hit his stumps.
The Black Caps were unable to break free from the early shackles and tight lines from Chris Jordan including two key scalps heavily dented their progress.
In response, Vince batted with remarkable fluency as his risk-free shots fetched him boundaries on numerous occasions.
Contrary to the unbridled aggression exemplified by brutish power-hitting, Vince merely found the gaps with his orthodox drives to assert England's dominance in the game.