Chasing a revised target of 145 in 23 overs following a long rain interruption, India romped to a 10-wicket victory under the Duckworth-Lewis method as Skipper Rohit Sharma and fellow opener Shubman Gill got them across the line with 17 balls left.
Rohit was not out on 74 after smashing six fours and five sixes, while Gill made an unbeaten 67.
India had earlier let Nepal off the hook after opting to bowl as Shreyas Iyer dropped Kushal Bhurtel in the opening over and Virat Kohli made a mess of another chance in the next to hand Aasif Sheikh a lifeline.
Bhurtel got another reprieve when wicketkeeper Ishan Kishan put down a simple catch off Mohammed Shami, but fell to Shardul Thakur for 38 while Sheikh scored 58 - his 10th half-century in one-day international cricket.
But Ravindra Jadeja (3-40) tore through the middle-order and Mohammed Siraj (3-61) also got in on the act before rain briefly halted play at 178-6. Nepal then rode on Sompal Kami's 48 lower down the order to finish with 230 in 48.2 overs.
More rain followed after India began their chase, prompting match officials to revise the target after a lengthy delay.
India advance to the next stage of the tournament with three points after their meeting with Pakistan at the same stadium was washed out on Saturday.
The south Asian neighbours, who only face off in multi-team tournaments due to soured political relations, are set to clash again in the next stage at the weekend.
