Shikhar Dhawan's 12th one-day international century steered India to an emphatic eight-wicket win in the series decider after Sri Lanka collapsed in Visakhapatnam on Sunday.
Sri Lanka were going along nicely on 136-1 in the 23rd over, but spinners Kuldeep Yadav (3-42) and Yuzvendra Chahal (3-46) did much of the damage as they collapsed to 215 all out.
Upul Tharanga fell just five short of a hundred and Sadeera Samarawickrama made 42 in a second-wicket stand of 121, but the tourists' innings fell to pieces and India eased to a 2-1 victory after losing the opening match of the series.
A masterful innings from Dhawan, who finished 100 not out off only 85 balls, sealed India's eighth straight series win in the 50-over format and Shreyas Iyer (65) struck back-to-back half-centuries in his first ODI series as Sri Lanka were given another harsh lesson ahead of a new era under Chandika Hathurusingha.
Sri Lanka recovered smartly from the early departure of Danushka Gunathilaka (13), with Tharanga particularly aggressive, taking Hardik Pandya for five successive fours in the ninth over before reaching fifty from only 36 balls.
Samarawickrama was put down on 29 - a tough chance to Dinesh Karthik at midwicket - but it did not prove too costly as he holed out to become Chahal's first victim soon after.
Tharanga brought up 1,000 ODI runs this year by hammering Chahal over long-on for six, repeating the feat in the leg-spinner's next over before perishing to Kuldeep, stumped by MS Dhoni as he stretched forward.
Niroshan Dickwella fell later in the same over and Sri Lanka began to lose wickets regularly, Angelo Mathews and Asela Gunaratne (both 17) the only other men to reach double figures as India turned the screw.
Rohit Sharma stole the show with a magnificent double century in the second ODI, but the stand-in captain fell for only seven when Akila Dananjaya bowled him with a delivery that drifted in.
Dhawan and Iyer were untroubled on a good surface, though, using their feet expertly against the spinners and latching onto far too many loose deliveries to put India well on course to reach their target.
Iyer outlined his promise once again, outscoring Dhawan and cashing in on Mathews' failure to hold on to a difficult chance at first slip when he had 25 to his name, smashing Sachith Pathirana for six and reaching 50 off only 44 deliveries.
Dhawan raised his bat after a slog-sweep for six off Dananjaya cleared the ropes and went on to pass 4,000 ODI runs after Iyer offered a simple catch to Suranga Lakmal off the bowling of Thisara Perera.
Karthik (26) successfully reviewed when he was given out leg before when the ball struck his inside edge before hitting the pad and another powerful sweep to the boundary took Dhawan to a deserved hundred as India sealed victory off only 32.1 overs.