Contributions from B Sai Sudharsan (46, 31 balls), captain Vijay Shankar (33, 26 balls) and R Sanjay Yadav (32, 22 balls) helped the defending champions chase down Kerala's 181 for 4 in 20 overs.
Earlier, a blistering 65 of 26 balls by Vishnu Vinod helped Kerala overcame a slow start to score a formidable total despite skipper Sanju Samson's (0) failure.
Sent into bat by Tamil Nadu, Kerala openers Rohan Kunnummal (51, 43 balls) and the aggressive Mohammed Azharuddeenn (15) could not get going against some good bowling. When the two appeared to be picking up pace, leg-spinner Murugan Ashwin (1/20) struck for Tamil Nadu when he had Azharuddeen caught by Sandeep Warrier, who hurt himself in the process.
Sachin Baby (33, 32 balls) and Kunnummal began to accelerate with the former scoring the bulk of the runs.
Kunnummal became the first of left-arm spinner Sanjay Yadav's two victims, when he was stumped by N Jagadeesan as he jumped out for a big hit. Samson, from whom much was expected, fell to a super catch by Ashwin as he tried to hit a delivery from Yadav.
Vishnu Vinod, who walked in at the fall of the captain, simply toyed with the TN bowling and smashed sixes at will. He went berserk and reached his 50 from just 22 balls. The 18th over went for 23 runs as he hit three sixes. First, he hammered Warrier for two maximums before the pacer went out of the attack due to an injury. The last three overs cost 62 runs as Kerala went from 119 for 3 in 17 overs to 181 at the end of the 20th over.
In reply, Tamil Nadu opener Jagadeesan hit the fifth ball of the first over for a six before C Hari Nishaanth took over.
Medium-pacer K M Asif dismissed the dangerous Jagadeesan for seven. Nishaanth and Sai Sudharsan added 32 runs in good time before the latter was bowled by Sudhesan Midhun.
Then a brisk 57-run stand between Sai Sudharsan and Vijay Shankar, who hit two big sixes, set Tamil Nadu on the road to victory.
Sanjay Yadav, who came in at the fall of Sai Sudharsan's wicket, showed his big-hitting skills and forged a 30-run partnership with the captain. He fell with four runs required for victory.
Shahrukh Khan underlined his finishing skills by smashing two big sixes in his nine-ball 19 to see Tamil Nadu home. Brief scores: Kerala 181 for 4 in 20 overs (Vishnu Vinod 65 not out, Rohan Kunnummal 51, Sanjay Yadav 2/23) lost to Tamil Nadu 187 for 5 in 19.3 overs (B Sai Sudharsan 46, Vijay Shankar 33, Hari Nishaanth 32, Sanjay Yadav 32, Unnikrishnan Manukrishnan 3/26) by five wickets.