[4] Along with the ADF, it forms part of the larger Australian Defence Organisation (ADO) and is accountable to the Parliament of Australia, on behalf of the Australian people, for the efficiency and effectiveness with which it carries out government policy.

The executive head of the department, who leads it on a day-to-day basis, independent of a change of government, is the Secretary of the Department of Defence (SECDEF), currently Greg Moriarty.

[5] A major departmental reorganisation occurred in the lead-up to World War II.

[6] In May 2022, the Canberra Times reported that department had been renamed Defence Australia.

The ADO diarchy is a governance structure unique in the Australian Public Service.