The India captain hit four sixes and as many fours to help India chase down a target of 91 runs with four balls to spare in a match that was reduced to eight overs due to a wet outfield.
Earlier, Matthew Wade played an unbeaten knock of 43 off 20 balls to bowl Australia out for 90 for five.
Wade hit four fours and three sixes – all in the final over from Harshal Patel (0/32) – while captain Aaron Finch scored 31 off 15 when Rohit invited Australia to bat in a match in which Two-and-a-half hours.
Chasing down the target, Rohit made his intention clear as he, in a spree of six sixes, gave India a flying start by delivering three monstrous hits in the first over to Josh Hazlewood.
The India opener then deposited a slow delivery from Pat Cummins (1/23 in 2 overs) into the stands before lifting Adam Zampa (3/16 in 2 overs) for another maximum at long-off.
But the spinner came back to disturb the stumps of KL Rahul (10), who looked to go for the slog-sweep.
Virat Kohli (11) then hit a boundary off Daniel Sams, followed by another boundary off Zampa’s head.
However, the spinner won the battle of wits as his quick delivery stunned the Indian and removed the stumps.
The very next ball, Zampa trapped Suryakumar Yadav (0) and bowled India out for 55 for 3 in 4.3 overs.
Unfazed by the fall of wickets, Rohit continued to strengthen with cover of an over and then Sean Abbott pulled an over short fine for 11 runs.
Hardik Pandya hit a boundary off Cummins but he could not last long and Finch was dismissed in the seventh over.
Designated finisher Dinesh Karthik again played his part to perfection, taking the remaining runs off Sams’ delivery for a six and a four.
Earlier, Australia were looking to make a show for the capacity crowd at the VCA Stadium, but Axar Patel (2/13 in 2 overs) took two wickets in an impressive spell to leave them at 31 for 3.
Jasprit Bumrah (1/23 in 2 overs), who has been out of action since the end of the England tour with a back injury, produced a sensational yorker during his spell to get rid of the dreaded finch.
However, Wade made sure to add 44 runs in the last 18 balls with Steve Smith (8).
Harshal’s evening was another memorable one as he conceded 32 runs in his two overs without taking a wicket.
Both the teams will now travel to Hyderabad for the series-deciding third T20I match on Sunday.