The primary role of the Department of Defence is to support the Minister as head of the department and in particular to provide policy advice and support on Defence matters, including assistance with policy formulation and the implementation of policy as directed by the Minister.

The civil element also has a number of specific roles which include:

the management of legal, regulatory and litigation policy and related matters on behalf of the Minister
the management of the department's human resources and industrial relations
the coordination of the delivery of security, emergency and community services by the Defence Forces