Set 266 to win, New Zealand were bowled out for 210 in 44.5 overs despite a fighting 75 from Dean Foxcroft. The chase never fully recovered after early setbacks, with Bangladesh’s bowlers striking at regular intervals.
Mustafizur Rahman starred with the ball, claiming a brilliant 5-wicket haul to dismantle the lower order, while Nahid Rana picked up two crucial wickets.
Captain Mehidy Hasan Miraz also chipped in with two scalps.
Earlier, Bangladesh recovered from 32/3 to post 265/8, thanks to a superb century from Najmul Hossain Shanto, who scored 105.
He was well supported by Litton Das with 76, as the duo added a crucial partnership to rebuild the innings.
New Zealand’s Will O’Rourke had earlier put Bangladesh under pressure with three early wickets, but the hosts fought back strongly.
The win capped a strong comeback for Bangladesh after losing the opening match, sealing the series dominantly.