Nasum has played 20 First-class, 36 List-A and 17 T20 matches in the domestic circuit taking 75, 43 and eight wickets respectively.
Along with Nasum, Hasan Mahmud is the only other uncapped player in the squad. Hasan was also a part of Bangladesh team during their T20I series against Pakistan earlier this year.
Mohammad Saifuddin made a comeback to the T20I squad after a five-month long gap due to injury.
Mahmudullah will continue to lead the Tigers in the shortest format of international cricket.
The first match of the series will take place on March 9 while the other match will be played on March 11 at Sher-e-Bangla National Cricket Stadium.
Bangladesh T20I squad for Zimbabwe series: Mahmudullah Riyad (Captain), Tamim Iqbal, Soumya Sarkar, Naim Sheikh, Liton Das, Mushfiqur Rahim, Afif Hossain, Mohammad Saifuddin, Mahadi Hasan, Aminul Islam Biplob, Mustafizur Rahman, Shafiul Islam, Al-Amin Hossain, Hasan Mahmud and Nasum Ahmed.