Lieutenant Colonel Haji Mohammad Norfahssin bin Haji Abdul Karim joined the Royal Brunei Armed Forces in September 1993 after his studies at University of Brunei Darussalam. Upon completion of basic military training at Training Centre, Royal Brunei Armed Forces, he attended officer cadet training at the Army's Officer Cadet School Waiouru, New Zealand in July 1994. A graduate and commissioned as a Second Lieutenant of the Officer Cadet School of New Zealand in June 1995.
His initial appointment was as a rifle platoon commander at First Battalion Royal Brunei Land Force and subsequently throughout his military career served in a number of appointments at command, staff and instructional His tour include Adjutant of First Battalion Royal Brunei Land Force, Officer Commanding at Second Battalion Royal Brunei Land Force and Second-in-Command of Third Battalion Royal Brunei Land Force. He was Head Tactics Wing and Officer Commanding at Recruit Company and Course Company for a Training Institution. Latterly assumed the appointment of Staff Officer One, Inspectorate Unit Royal Brunei Armed Forces on 01 August 2012.
He attended courses (military career or specialized) abroad and instate. He attained the National Examination Board in Occupational Safety and Health (NEBOSH) International General Certificate (IGC) in Occupational Health and Safety and also the Institution of Occupational Safety and Health (IOSH) Managing Safely. A graduate of the Royal Thai Army Command and General Staff College (CGSC) Class 87 (October 2008 to September 2009) at the Command and General Staff College, Royal Thai Army, Bangkok Thailand and awarded with the Command and General Staff College's Academic Standing Badge (Kem Senathipataya). He also completed the 12th Executive Development Programme (EDP) on Public Policy and Management for Senior Government Officials 2015 (September to December 2015) conducted in cooperation with Sultan Haji Hassanal Bolkiah Institute of Defence and Strategic Studies, Ministry of Defence, Negara Brunei Darussalam and Lee Kuan Yew School of Public Policy (LKY School), National University of Singapore.
Most recently, he has been a Staff Officer One at the Inspectorate Unit, Royal Brunei Armed Forces and Directorate Personnel, Ministry of Defence for the last eight years. He returned to the Royal Brunei Land Force as Head Inspectorate on 27 November 2020.
His operational experience was in the Republic of the Philippines as the Second 10-man contingent of the International Monitoring Team (IMT)-Mindanao (15 September 2005 to 01 September 2006) as Deputy Head of Contingent and was awarded the Combat Commander's (Kagitingan) Badge (Level of Battalion Commander) from General Headquarters, Armed Forces of the Philippines (30 August 2006) in recognition of his role as IMT. He was also awarded the Meritorious Service Medal (Pingat Jasa Kebaktian – PJK) in recognition of his contribution as IMT.
He is married to Sarinah binti Haji Bagol and blessed with two grown up children, his spare time is filled with family and walking.