His works include Most Welcome, Ami Shudhu Cheyechi Tomay, Ostitto, Ami Tomar Hote Chai, Nabab LLB, Makeup, Koshai, Amanush, Radio and the upcoming film Dard.
He directed Ami Shudhu Cheyechi Tomay in 2014; it was the first co-production film between Bangladesh and India.
The same year, Mamun worked on Ami Tomar Hote Chai, starring Bappy Chowdhury and Bidya Sinha Saha Mim.
[8] In December 2020, the first part of his fictional courtroom drama Nabab LLB was released on Bangladeshi streaming services.
The unfavourable depiction of the Bangladeshi police force handling the case of a sexual assault victim in the movie led to Mamun's arrest on 25 December 2020, along with the actor who portrayed a policeman, Shaheen Mridha.