Shreyas Iyer scored his maiden ODI hundred to put India on top. Half-centuries from Virat Kohli and KL Rahul too helped India take full control of the first ODI at Hamilton.
Rahul and Iyer's stand after Kohli's innings (51) was cut short by Ish Sodhi put New Zealand on the backfoot.
Earlier, New Zealand got a couple of quick breakthroughs after debutants Mayank Agarwal and Prithvi Shaw brought up India's fifty inside 8 overs.
Grandhomme dismissed Shaw for 20 while Southee sent back Agarwal for 31. Earlier, New Zealand won the toss and opted to field first against India in the first ODI at Hamilton.
India handed debuts to Mayank Agarwal and Prithvi Shaw, while the hosts gave the ODI cap to Tom Blundell in place of injured regular captain Kane Williamson.