Rebecca Rolls made a polished 86 as New Zealand's excellent all-round performance gave them a 1-0 lead in the three-match series.
The White Ferns were determined to return to winning ways after rain denied them in the opening game and raced to their target with almost 20 overs to spare.
Ireland's total was built around an innings of 56 by Catriona Beggs.
She shared a third wicket stand of 53 with Miriam Grealey (24), but once they had gone, Frances King and Haidee Tiffen cut through the lower order.
The last six wickets went down for 19 runs as King finished with four for 27 from seven overs and Tiffen claimed three for 22.
The home side needed early wickets but Rolls and opening partner Kate Pulford (40) were in aggressive mood and effectively settled the issue with a stand of 106.
Both eventually fell to off-spinner Catherine O'Neill, who completed a full 10 overs for figures of two for 43.
It was only a temporary setback, however, as captain Emily Drumm steered her side home with 40 not out.
The final game takes place at College Park on Sunday.