Jorge Pereyra Diaz, returning to the side after serving a one-match suspension, scored a brace in the space of three second-half minutes (52nd, 55th) before Adrian Luna (90th) crowned the team's performance with a world-class goal from a free-kick.
The result means Kerala are back in the top four with 30 points from 18 matches. Chennaiyin, already out of the semis race, remained in the eighth spot with 20 points from 19 matches.
Both teams looked keen to attack from the get-go, Kerala keeping more of the ball and Chennaiyin looking to hit them on the counter. With nothing to lose, Chennaiyin played with more freedom than they did all season, Anirudh Thapa underlining their intent with a lovely ball out wide to Edwin Vanspaul who sent in a cross for Lukasz Gikiewicz who was ruled offside.
Minutes later, Jobby Justin headed inches wide of target from a Vladimir Koman corner at the far post. Closer to halftime, Kerala got a glorious opportunity to draw first blood, Adrian Luna and Alvaro Vazquez combining to set up Jorge Diaz who fluffed his lines from a couple of yards out with the goal gaping wide open.
Kerala started the second half on the front foot with Diaz making amends for his miss in the first period by scoring a quickfire brace. First, the Argentine outfoxed his marker to bunt the ball in past the keeper, and then three minutes later converted a rebound after Sanjeev Stalin's effort came off the crossbar.
It was a brilliant move that saw Vazquez back-heel for Stalin who burst forward and showed sublime skills to beat his man. Diaz was at the right place at the right time to thump home Stalin's rebound and make it 2-0 for the yellow army.
Luna then racked up a world-class goal, sending a knuckle-ball free-kick over the ball and dipping just in time to beat Vishal Kaith all ends up in Chennaiyin goal.