Both sides were locked 1-1 after extra time that led to the shoot-out.
No wonder ATK's marquee co-owner Sourav Ganguly along with Sanjeev Goenka were ecstatic beating a franchise which is co-owned by Sachin Tendulkar.
India international Jewel Raja successfully converted the fifth penalty as the 55,000 capacity crowd at the Nehru Stadium were stunned into silence.
In that 2014 final, ATK had beaten Kerala Blasters 1-0 in Mumbai.
More From This Section
Besides Jewel Raja, Sameehg Doutie, Borja Fernandez and Javier Lara found the target in the shootout while Iain Hume's shot was blocked by Kerala goalkeeper Graham Stack.
For Kerala, who came into the match after winning six times on the trot before today's match, Antonio German, Kervens Belfort and Mohammed Rafique scored while Elhadji Ndoye and Cedric Hengbart failed to find the target.
The match was devoid of any extraordinary moments or twists and turns, which was there in the summit clash of last season.
ATK's tournament second highest goal-scorer Hume was quiet for most part of the match as he was not given space by Kerala defenders.
There were no surprises in the starting eleven of both the teams with ATK bringing in marquee player Helder Postiga, league second highest scorer Iain Hume and Sameehg Doutie after 'resting' them in the second-leg semifinals against Mumbai City FC.
Kerala, on the other hand, left out their second-leg semifinal penalty shootout win hero sandip Nandy in favour of former Arsenal goalkeeper Graham Stack.
In the 10th minute, Kerala's Kervens Belfort played Mohammed Rafi through inside the box and the former India forward looked to finish it with a powerful shot but Jose Arroyo was just on time to block it.