Chasing 153 to take a 1-0 lead in the three-game series, Naim remained unconquered on 66 after crafting a 101-run stand with Soumya (50) as the visitors coasted to the win with seven balls to spare at the Harare Sporting Club on Thursday.
Zimbabwe, who won the toss, made a good start with Regis Chakabva transferring his ODI form to the T20 format and scoring 43 to guide Zimbabwe to 91-3 after 10 overs.
But they added only 61 more runs as wickets tumbled in the next nine overs and were bowled out with one over to spare. Mustafizur Rahman took 3-31.
The sides meet again in the three-game series on Friday and Sunday. Bangladesh beat Zimbabwe in their one-off test this month and wrapped up a 3-0 win in the one-day international series this week.
[With input from Reuters]