While the result was primarily tethered to Williamson's fortunes, Colin de Grandhomme provided able support in a fifth-wicket partnership of 81. He also made his highest T20I score, 41 off 22 balls at No.6. Tom Bruce was run out for seven on debut.
The catalyst to the victory came in the 14th over when a Williamson four from a slog sweep off Shakib Al Hasan scraped over deep mid-wicket's head. He followed up by clobbering a six whose only chance of being caught was by members of the corporate boxes.
In the process of creating cricketing art, Williamson became the fifth-equal fastest batsman alongside Chris Gayle to reach 1000 T20I runs in his 34th innings. He sits behind Virat Kohli (27 innings) and Kevin Pietersen, Alex Hales and Faf du Plessis (32).
Earlier, a rookie New Zealand bowling attack restricted Bangladesh to 141 for eight.
The Black Caps nagging line and length, led by first-change Lockie Ferguson with two wickets from his first two balls in the format, saw pressure mount. Sabbir Rahman swatted a 148km/h thigh-high full toss to mid-on, followed by Soumya Sarkar guiding a catch to gully.
For the hat-trick ball, Mahmudullah clamped down on a 147km/h Ferguson yorker at the base of off stump. That was followed by a chin-high bouncer which left the Bangladeshi No.5 risking whiplash. He was unfazed and used his professional nous to top score with 52 from 47 balls before Ferguson bowled him in the final over. The Aucklander finished with figures of three for 32, joining Nathan Astle, Kyle Mills, Jeetan Patel and Michael Bates as other New Zealand bowlers who have taken three wickets on T20I debut.
Fellow T20 bowling apprentice Ben Wheeler also showed composure until a final over in which he sprayed three wides. He finished with two for 22. His initial first three-over spell conceded 13 runs and included 11 dot balls. He took the prime wicket of Tamim Iqbal.
The opener pulled to deep square leg where Bruce could be forgiven if he had waited with clammy palms.
The best partnership Bangladesh could muster was 37 between Mahmudullah and Shakib Al Hasan for the fifth wicket.
Mitchell Santner, with 17 wickets from 10 T20Is before the match, became the leader of the attack in the rest-enforced absence of Tim Southee and Trent Boult.
With Anderson playing as a specialist batsman, the rest of the bowling unit had a tally of nine wickets between them before the game.
Santner continues to impress as he assumes more of a senior pro role 19 months into his international career. He finished with one for 20, but perhaps the highlight was the steepling take he took off Shakib who made 14 off as many balls.
The all-rounder swung into the legside off de Grandhomme. Santner had time to phone-a-friend or ask-the-audience before it descended through the backdrop of Norfolk pines on Marine Parade. Fortunately it was no 50:50. He produced the correct answer after padding back 10m from the inner circle.
