New Zealand 195 for 7 (Munro 101, Bruce 59*, Rubel 3-37) beat Bangladesh 148 (Sabbir 48, Sodhi 3-36, Williamson 2-16) by 47 runs
Scorecard and ball-by-ball details
Colin Munro's marauding 52-ball hundred - his first in T20 internationals - powered New Zealand to a series win with a game to spare. Munro struck seven sixes and seven fours to lead the hosts to 195, which proved 47 too many for Bangladesh.
New Zealand, though, had to deal with the anxiety of Luke Ronchi leaving the field in the eighth over of the chase because of a groin injury. He did not return, with rookie Tom Bruce taking the wicketkeeping gloves.
Bangladesh threatened briefly with a rapid 68-run stand between Soumya Sarkar and Sabbir Rahman, but lost their last seven wickets for 44 runs to be dismissed for 148 in 18.1 overs.
Bangladesh had started positively, though, after opting to bowl in Mount Maunganui. Their captain Mashrafe Mortaza struck with the first ball to remove Ronchi, before the spinners made further inroads to reduce New Zealand to 46 for 3 within six overs.
Munro took charge and added 123 runs - a New Zealand record for the fourth wicket in T20Is - with Bruce, who helped himself to an unbeaten 59 off 39 balls, including five fours and a six.
Munro signalled his intent with a blast down the ground off Mashrafe in the first over. Despite the loss of Ronchi, Williamson, and Corey Anderson, Munro went on a boundary-hitting spree. He hit Rubel Hossain for back-to-back fours in the second over and then launched offspinning allrounder Mosaddek Hossain for two sixes in the eighth over.
Munro reached his fifty off 31 balls in the 11th over before hammering Shakib Al Hasan for a six over cover and four to long-on. He found excellent support from the newcomer Bruce, who rotated the strike well in addition to putting the bad balls away.
Munro hit top gear when he nailed Mahmudullah behind square for two sixes in three balls in the 13th over. Mahmudullah eventually conceded 28 runs off that over as Munro zoomed from 64 to 92.
He brought up his century with a quick single in the 16th over, becoming the third New Zealand batsman, after Brendon McCullum and Martin Guptill, to score a T20I hundred.
Munro was dismissed in the next over by Rubel, who proceeded to dismiss Colin de Grandhomme and Jimmy Neesham. He also ran Mitchell Santner out and finished with impressive figures of 3 for 37.
Bangladesh's start strangely mirrored New Zealand's. The visitors lost three early wickets before the fourth-wicket pair lent the innings some impetus. Imrul Kayes holed out in the first over, Tamim Iqbal fell to a horrible mix-up in the fourth, and Shakib chipped Ben Wheeler to cover-point, leaving his team at 36 for 3 in 4.1 overs. The early losses put additional pressure on Sarkar, who had managed only 1 and 0 in his last two innings.
He regained form with a glance past fine leg and two sixes over long-on. He went on to hit Trent Boult for two fours in the 11th over before top-edging a pull to short fine leg. He had made 39 off 26 balls.
Sabbir played some adventurous shots, including a scoop over the wicketkeeper's head and a number of blasts over long-on, but sliced Ish Sodhi to long-off for 48. Sodhi then combined with Williamson to derail Bangladesh's chase.
Sabbir missed out on a fifty despite having batted so well with his three sixes, ranging from the scoop over the wicketkeeper's head to big blasts over long-on.
Ish Sodhi, who conceded 16 off his first over, removed Sabbir before taking the wickets of Mahmudullah and Mashrafe Mortaza as Bangladesh sunk fast in the chase.
Mitchell Santner's ripping catch at long-on to dismiss Mosaddek Hossain was another highlight in a game in which New Zealand ran into trouble twice, but bounced back strongly to wrap up the series.
Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84