Niall O'Brien scored his maiden one-day international hundred but Ireland were unable to spring a surprise against New Zealand.
Match scores (Dublin)
New Zealand win by 51 runs
New Zealand inns: 287-7 (50/50 overs. Broom 79, Taylor 52, Worker 50; McCarthy 2-59)
Ireland inns: 238 all out (45.3/50 overs. O'Brien 109; Santner 5-50, Kuggeleijn 3-41)
Match report
Niall O'Brien scored his maiden one-day international hundred but Mitchell Santner's five-wicket haul helped New Zealand avoid a shock defeat against Ireland in Dublin.
After New Zealand had set Ireland 290 to win the second tri-series match, O'Brien gave the hosts hope with a century that featured nine fours and five sixes.
But the number three ran out of partners and was dismissed for 109 by Santner as the left-arm spinner finished with five for 50 in New Zealand's 51-run victory.
Neil Broom, Ross Taylor and George Worker had earlier all scored half-centuries to help the Black Caps to 289 for seven from their 50 overs.
The next tri-series fixture on Wednesday sees New Zealand take on Bangladesh, whose opener against Ireland was washed out.