Set a meagre 137 to win, New Zealand hardly broke a sweat in pursuit of the target, losing no wickets and finishing off the game in 16.1 overs as both Colin Munro and Martin Guptill made half-centuries.
The two brought up their 50-run stand in the 7th over and crossed the 100-run mark in the 13th over before finishing the match 3.1 overs later.
Earlier, a clinical display from the New Zealand pacers shot down Sri Lanka for just 136.
Matt Henry dealt the early blows as he ended with three while Lockie Ferguson cleaned up the innings to keep Sri Lanka to an extremely modest score.
New Zealand pacers were ruthless and even though there were some crisp strokes, the Sri Lanka batsmen never really got the opportunity to settle in.
Dhananjaya de Silva and Jeevan Mendis fell to the pace of Ferguson while in between Angelo Mathews inside-edged a delivery from Colin de Grandhomme to the keeper.
New Zealand 137 for 0 (Guptill 73*, Munro 58*)
Sri Lanka 136 (Karunaratne 52*, Ferguson 3/22, Henry 3/29)>