India restricted Sri Lanka to a modest 100 for eight after Bisht claimed a hat-trick in the last over in which the hosts lost four wickets and scored just three runs.
Chamari Atapattu was the top-scorer for the home team with her 28-run knock. Skipper Shashikala Siriwardene (23) was the other major contributor for Sri Lanka.
Chasing 101 to win, Poonam Raut (45) and skipper Mithali Raj (28) shared an unbeaten 64-run second-wicket stand to guide the side to its very first win of the tournament with 5.2 overs to spare.
India had lost all three Group stage matches to reach a stage where they needed to beat Sri Lanka to keep its right of playing in the next edition of the event.
Sri Lanka were already struggling at 99 for four when Bisht came to bowl the last over of the innings and piled on the hosts' misery with her superb bowling.
She first dismissed Dualani Surangika (10), having her caught by Nagarajan Niranjana and then caught Yasoda Mendis (10) off her own bowling in the next ball.
Eshani Kaushalya (0) could not survive the hat-trick ball as she was caught by Jhulan Goswami. More drama was to follow as Sandamali Dolawatte ran herself out while attempting a single on the penultimate ball of the innings. MORE
