MI's win Friday ended CSK's winning streak of five games at home this season.
Rohit top-scored with 67 from 48 balls with the help of six fours and three sixes to help MI post 155 for four on a slow and turning Chepauk surface after being sent into bat.
And then MI bowlers led by Sri Lankan Lasith Malinga (4/37) bundled out CSK for 109 in 17.4 overs, the defending champions' lowest total at home.
Besides Malinga, Krunal Pandya (2 for 7 in 3 overs) and Jasprit Bumrah (2 for 10 in 3 overs) did the damage.
By virtue of this win, MI has jumped to the second spot in the table with 14 points from 11 games. Despite the loss, CSK still lead the chart with 16 points from 12 matches.
Defending the total, MI spinners appeared to return the compliment after CSK tweakers had done a superb job in restricting the visiting team's batsmen.
Murali Vijay (38) was the top-scorer for CSK before being caught smartly by Suryakumar Yadav off Bumrah. Dwayne Bravo (20) and Mitchell Santner (22) were the only other batsmen of the home team to reach double figures.
Shane Watson, who hammered the SRH attack into submission in last Tuesday's game, hit Malinga for two fours but clipped a poor delivery from the Sri Lankan straight into the hands of Rahul Chahar at short fine-leg. He fell for eight in the first over to leave CSK at nine for one.
Skipper Suresh Raina didn't look comfortable during his brief stay, before skying one to Suryakumar off Hardik Pandya for just two.
Ambati Rayudu, who has found runs hard to come by this season, endured another failure. He was castled by Krunal Pandya for a duck with a delivery that came in with the arm as CSK slipped into further trouble.
Kedar Jadhav's poor form continued as he too was castled by Krunal Pandya.