The 35-year-old hit an unbeaten 99 from 133 balls to take England to a workmanlike victory with 35 balls to spare.
Root hit nine fours in making his fifth successive score of over 50 in an ODI. He might have liked one more run for his century but it was more important that he got England over the line.
"That's not what you play for," player-of-the-match Root said referring to the missed century. "Just to be there at the end and get the job done is probably the best feeling you can get in cricket.
"You play to win games and this series is very much alive now - which is what we intended at the start today. Sometimes you've got to win scrappy and ugly and we now go to the Lord's with everything to play for.
"The challenge is can we do it again at Lord's when the pressure is on against a brilliant team? But for us to stand up and play like that I think shows where we are and is a good benchmark for us."
India, who were bowled out with six overs to spare, had set an under-par target of 233.
The world's top-ranked side, who were 1-104 at one point, lost their last seven wickets for 55 runs.
Shreyas Iyer top scored for the visitors with 66 while Virat Kohli made 65 - his 132nd innings of 50 or more in an ODI - but the rest of India's middle-order fell away alarmingly.
Jofra Archer, who was on a hat-trick after removing Axar Patel and Shivam Dube in successive balls - took 3-47 and Gus Atkinson 3-50 - his best figures in an ODI.
Jasprit Bumrah provided a late flurry with an unbeaten 20 – his highest ODI score - and dismissed Ben Duckett with the first ball of the England innings.
Duckett's opening partner Jacob Bethell followed quickly but even though Harry Brook and Jos Buttler departed to rash shots, Root was the constant in the England reply.
Root and Will Jacks put on 72 for the sixth wicket before he saw England home in the company of Atkinson who made 23 not out off 16 balls.
"It was quite disappointing to be honest," said India captain Shubman Gill.
"We thought 300-310 would be a good total after 25 overs when we were in a good position, but we lost too many wickets in the middle overs.
"We know our tailenders are not the best batsmen but I think we expected a bit more from our lower middle order. We were not able to capitalise on the start that we got."
Agencies
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