Chasing a target of 285, Mitchell was 131 not out and received good support from Will Young (87) as the Blacks Caps reached the total with more than two overs to spare.
The run-chase did not get off to the best of starts for New Zealand as they lost opening pair Devon Conway (16) and Henry Nicholls (10) woith 46 runs on the board.
Young and Mitchell though steadied the ship and some more with a match-winning partnership of 162 for the third wicket.
The stand came to an end in the 38th over when Young skied a catch to mid-wicket of spinner Kuldeep Yadav (1-82).
Glenn Phillips then joined Mitchell in the middle and struck a composed 32 not out from 25 balls as the Kiwis hit the winning runs in the 48th over.
Earlier, KL Rahul hit an unbeaten 112 to guide India to a total of 284-7 in their 50 overs after being sent in to bat the toss.
Home skipper Shubman Gill chipped in with 56 but there was just not enough for Rahul from other top-order batters as India just over above the 180-run mark.
The series decider will be played in Indore on Sunday which will be followed by five T20Is.
New Zealand captain Mitchell Santner insists he is proud of his players despite falling to a big defeat against India in the T20 World Cup final in Ahmedabad on Sunday.
India captain Suryakumar Yadav says the team's next target is to win the Olympic gold medal in Los Angeles in 2028 after capturing the T20 World Cup trophy on home soil.
India cemented their dominance in white-ball cricket by defeating New Zealand by 96 runs in Ahmedabad to become the first men's side to win the T20 World Cup three times and the first to defend the title successfully.
New Zealand captain Mitchell Santner insists they are ready to cause an upset as they prepare to face hosts India in the ICC Men's T20 World Cup final on Sunday in Ahmedabad.
