Rajeshwari Gayakwad got her first wicket after Nilakshi de Silva played on to her stumps while trying to cut a ball close to her body.
India lost Shafali Verma and Jemimah Rodrigues cheaply in the run chase.
However, both the batters did well in the tournament, with Shafali getting back to form and Jemimah making a successful comeback from injury.
The elegant Mandhana played some exquisite strokes on way to completing the formality alongside skipper Harmanpreet Kaur (11 not out off 14).
Smriti’s effort included three sixes and six boundaries.
Fittingly, she sealed the win with a maximum off Oshadi Ranasinghe.
The win is a shot in the arm for India’s preparations for the T20 World Cup next year.
The Indians took a lap of the Sylhet International Cricket Stadium and, in a fine gesture, got clicked with the entire groundstaff after their triumph, which was witnessed by a sizeable turnout.