Mithali Raj and Co recorded their fourth win on the trot as they defended a respectable 232/8 by restricting the island nation to 216 for 7.
The Indian eves also maintained a clean slate against their sub-continental neighbours since the 2013 World Cup, having never lost a single ODI in all meetings.
India's battery of slow bowlers have choked the opposition time and again during the tournament so far.
It was no different on the day as leg-spinner Poonam Yadav (2/23 in 10 overs) led the charge with twin blows, removing the dangerous Chamari Atapattu (25) and opener Nipuni Hansika (29).
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The seasoned Jhulan Goswami (2/26 in 8 overs) was parsimonious as ever, and provided important breakthroughs too.
Dilani Manodara Surangika (61 off 75 balls) batted well but found little support at the other end.
Skipper Raj marshalled her resources well after another impactful half-century, which was largely responsible for the decent total.
The match decisively swung in India's favour when the pint-sized Poonam, coming round the wicket, got the better of Atapattu with a flighted delivery that she tried to sweep but missed the line to be bowled.
Earlier, Deepti Sharma and Raj hit fine half-centuries to help India post a decent 232 for 8.
Deepti made 78 off 110 balls while Mithali (53 off 78) continued her good form with yet another 50 plus score to set the base for India's total after the early dismissal of openers Punam Raut (16) and Smriti Mandhana (8).
Electing to bat, India didn't have the best of starts as Mandhana departed early. She was soon followed by Raut in the 11th over that brought Mithali and Deepti at the crease.
The duo first resurrected India's innings and opened up once they got their eyes in.
They shared vital 118 runs for the third wicket to not only steady India's innings but create the perfect launchpad for others to follow.
But just when it was time for the Indian eves to launch the attack on Sri Lankan bowlers three quick wickets dragged them back.
But Veda and Harmanpreet took the onus upon themselves to keep up the ante before both got out in consecutive balls in the 49th over off Sripali Weerakkody to hand the Sri Lankan right-arm medium pacer, an opportunity to claim a hat-trick.
The Indian willow-wielders managed a decent 62 runs off the last 10 overs.
For Sri Lanka, Weerakkody (3/28) was the pick of the bowlers while Inoka Ranaweera (2/55) also returned with two crucial wickets.