The Ministry of Defence Brunei Darussalam, officially abbreviated as MinDef, is a cabinet-level ministry of the Government of Brunei. It is responsible for the national security and its military forces within the sultanate of Brunei Darussalam; the latter collectively known as the Royal Brunei Armed Forces (RBAF); Angkatan Bersenjata Diraja Brunei, (ABDB). MinDef is Brunei's ministry of defence; and was established on 1 January 1984, when Brunei Darussalam achieved independence from the United Kingdom. The Ministry of Defence leadership presently consists of a minister ; its incumbent is the Sultan of Brunei, Hassanal Bolkiah, who is also the Supreme Commander of the RBAF / ABDB. A deputy minister is second-in-command at the Ministry of Defence.

Abdul Razak bin Abdul Kadir is the current Ambassador of Brunei to Indonesia since 2024. He was formerly the Deputy Minister of Defence and the 12th Commander of the Royal Brunei Land Forces (RBLF) in 2022.