Stokes hit 52 after a quick knock of 54 from Dawid Malan, who was part of an emergency opening partnership with Harry Brook (25) because of injuries to Jonny Bairstow and Jason Roy. Brook has been controversially left out of England’s World Cup squad and was staking a claim for a late call-up.
New Zealand was on top after removing Joe Root for 6 to leave England 101-3 in the 21st over but Stokes and captain Jos Buttler, who was the top scorer with 72 off 68 balls on his 33rd birthday, steadied the innings with a partnership of 88.
Big-hitting Liam Livingstone weighed in with a lively 52 off 40, including three sixes, in a 77-run stand with Buttler before both fell to Tim Southee in the same over late on.
David Willey’s unbeaten 21 included a six down the ground off the last ball, and England seemed to have set a testing target.
Allrounder Rachin Ravindra had 3-48 off his 10 overs of spin.
New Zealand was always ahead of the run rate and batted with a great tempo. Opener Will Young — picked ahead of Finn Allen — hit 29 and Henry Nicholls 26 before Conway and Mitchell came together with the score at 117-2 and took England’s attack apart. Adil Rashid (1-70 in eight overs) came in for heavy punishment as he was smashed over the shorter boundaries by Mitchell especially.
Conway clinched the win with a straight six off Livingstone.
The second ODI is in Southampton on Sunday.