[1] Nazmul Ahsan joined the Bangladesh Civil Service on 25 April 1994 as an administration cadre in the 13th batch.
[1] In 2013, Nazmul Ahsan served as a deputy secretary in the Ministry of Power, Energy and Mineral Resources.
[3] On 6 December 2021, Nazmul Ahsan was appointed chairman of Petrobangla replacing ABM Abdul Fattah.
[6] In April 2022, he inaugurated a Mujib corner, named after President Sheikh Mujibur Rahman, at the Petrobangla headquarters in Karwan Bazar.
[7] On 11 December 2022, Nazmul Ahsan was appointed the secretary to the Ministry of Water Resources and is currently serving under this role.