Rohit blasted five fours and two sixes and shared 49 runs in 29 balls with Virat Kohli (28) and another 42 runs with Yuvraj Singh (12) to set the foundation for a good total.
Suresh Raina (41) then provided the late charge and added 26 and 32 with Yusuf Pathan (6) and Mahendra Singh Dhoni (10) to take India beyond the 150-mark.
Earlier, opener Murali Vijay gave India a positive start after skipper Dhoni won the toss and decided to bat at the Moses Mabhida Stadium here.
Vijay sliced Wayne Parnell between the wicketkeeper and slip for a boundary in the first over, before clobbering him for another four through square leg.
The Tamil Nadu batsman gave the same treatment to Makhaya Ntini in the next over before Morned van Wyk pulled off a blinder to dismiss Vijay as India lost their first wicket with 18 runs on the board.
However, Parnell found no respite as Virat Kohli picked up a boundary in the next ball through the fine leg area, before lifting Juan Theron over mid-wicket boundary in the next over.
In the fifth over, new man Rohit Sharma and Kohli went berserk, plundering three fours and a six off Ntini to accumulate 20 runs and take India to 49 for one.
However, skipper Johan Botha broke the partnership, removing Kohli. Looking for a pull, the Delhi batsman edged the ball straight to the stumps.
Botha and JP Duminy pulled things a bit in the next two over but Rohit had other plans as he blasted two fours and a six in successive balls in the 12th over to take India past the 100-mark.
Rohit reached his well-compiled half century with another boundary off Duminy but the bowler had the last laugh when he had the batsman holed out to Ntini at long on.
A terrible mix-up cost India another wicket when Yuvraj Singh was run out in the 14th over. Looking for a non-existent single, Yuvraj run upto new man Yusuf Pathan only to realise late that he had reached a point of no return.
Suresh Raina then joined Pathan and straightaway got into the business, blasting a four and a six off Theron but the pacer dismissed Pathan in his last delivery to leave India at 136 for five in 16 overs.
In the company of Dhoni, Raina then continued his rampage and brought up another six off Ntini in the 18th over, before hitting Theron for another maximum in the 20th over to take India past the 150-mark.
The left-hander blasted three sixes and two fours in his 23-ball innings and was out in the last ball of the Indian innings.