Colonel Khairil joined the Royal Brunei Armed Forces in 1989. After completing his training from the 10th intake of the Royal Brunei Armed Forces Boys Company, he was appointed as an Officer Cadet in October 1990 and underwent his officer cadet training at the Officer Cadet School, Waiouru, New Zealand in 1991. Upon commissioning in 1992, he served as a Platoon Commander, First Battalion Royal Brunei Land Force.
Throughout his military career, Col Khairil had the opportunity to hold various command, staff and instructional appointment. His command appointment includes Troop Leader Armoured Recce Squadron Support Battalion, Squadron Second in Command Armoured Recce Squadron Support Battalion, Officer Commanding Admin Company Second Battalion, Officer Commanding C Company Second Battalion, Officer Commanding Armoured Recce Squadron Support Battalion, Battalion Second in Command First Battalion and Commanding Officer Support Battalion whereas his staff appointments were Adjutant Support Battalion, Aide De Camp Commander Royal Brunei Armed Forces, Staff Officer Grade One J5 Joint Force Headquarters and Military Assistant to Commander Royal Brunei Armed Forces. He also had the opportunity to serve as the Officer Commanding Course Company Training Institute Royal Brunei Armed Forces as part of his instructional tenure during his service.
Col Khairil has attended various military career courses locally and overseas throughout his service. He was a graduate of Pakistan Command and Staff College in 2009 and the Royal College of Defence Studies 2016, in the United Kingdom, prior to assuming his current post as the Chief of Staff on 22 August 2016.
He also had the opportunity and honour to lead the 10th Batch of the Brunei International Monitoring Team in monitoring the ongoing peace process between the Government of the Philippines and the Moro Islamic Liberation Front in Mindanao, Southern Philippines as part of his overseas tour of duty experience.
In recognition of his service, Col khairil was awarded The Most Blessed Order of Setia Negara Brunei 4th Class (Darjah Setia Negara Brunei Yang Amat Bahagia Darjah Keempat, PSB) in 1998, The Most Honourable Order of Seri Paduka Mahkota Brunei (Darjah Seri Paduka Mahkota Brunei Yang Amat Mulia Darjah Ketiga, SMB) in 2012 and the Meritorious Service Medal (Pingat Jasa Kebaktian, PJK) recently in 2016 by His Majesty the Sultan and Yang Di-Pertuan of Brunei Darussalam
Col Khairil is married to Mazlina binti Hj Amir and blessed with 4 children (2 sons and 2 daughters).