Brig Jen Zamsari Abu Hasan hails from Kuala Sepetang, Taiping, Perak. He joined regular cadet training at the Royal Military College, Kuala Lumpur, in 1991 and was commissioned into the Royal Malay Regiment on August 5, 1993.

He has vast operational experience since reporting to 15 RMR as his first unit, where he operated in the southern and northern borders of Peninsular Malaysia as well as remote areas of Sarawak and Sabah. He continued for another total of nine months of operation in the western part of Sarawak during his tenure as Commanding Officer of 13 RMR in Sri Aman. His notable stint of operational experience included serving as Deputy Commander of Eastern Sabah Security Command (ESSCOM), Lahad Datu, in 2019 and Commander of the 8th Infantry Brigade based in Kelantan in 2020. His last appointment was Deputy Inspector General in the Malaysian Armed Forces HQ before recently taking over the appointment of Commandant of MASC.

Brig Jen Zamsari held key staff appointments related to strategic planning and development at the Army Headquarters. He has also served as military assistant or principal staff officer to top military leaders, as well as a military advisor to the Defence Minister in 2021. His professional military courses include the Technical Staff Officer Course in Pakistan, the Malaysian Armed Forces Staff College (MASC), and the Malaysian Armed Forces Defence College (MAFDC). During these courses, he attained academic qualifications in the field of strategic and defence studies and is an alumnus of both the University of Malaya (UM) and the National University of Malaysia (UKM). In 2022, he attended the National Resilience College (NRC) and was awarded a Fellow of the National Defence University of Malaysia (NDUM).

Brig Jen Zamsari has actively participated in international defence engagement, including Army to Army Talks in Australia, State Partnership Programme in the United States of America, and the Senior Workshop in International Rules Governing Military Operation (SWIRMO) in Russia. He is married to Puan Rosnani binti Muhammad and blessed with three sons and two daughters.