Greg Moriarty commenced as Secretary of the Department of Defence on 4 September 2017 and was reappointed for another 5-year term in September 2022.

The Secretary of the Department of Defence has primary responsibility for providing timely policy advice to Government, budget and resource allocation, and stewardship of the Australian Public Service workforce.

Greg first worked in Defence from 1986 to 1995, primarily in the Defence Intelligence Organisation. He also served in the Headquarters of the United States Central Command in the Persian Gulf during Operations Desert Shield and Desert Storm.

Prior to his appointment as the Secretary of Defence, Greg held senior roles in the Prime Minister's office, first as the International and National Security Adviser and then as Chief of Staff to Prime Minister Malcolm Turnbull.

In June 2015 Greg was appointed Commonwealth Counter Terrorism Coordinator in the Department of the Prime Minister and Cabinet. Greg was responsible for coordinating and implementing Australia's counter terrorism arrangements, in close partnership with the States and Territories.

Greg has extensive experience within the Department of Foreign Affairs and Trade (DFAT). Greg served in a number of senior roles, including as Deputy Secretary (2015), Ambassador to Indonesia (2010-2014), First Assistant Secretary, Consular Public Diplomacy and Parliamentary Affairs Division (2009-2010), Assistant Secretary, Parliamentary and Media Branch (2008-2009), Ambassador to Iran (2005-2008), Assistant Secretary, Maritime South East Asia Branch (2002-2005), and as the Senior Negotiator with the Peace Monitoring Group on Bougainville.

Greg holds a Bachelor of Arts Degree with Honours from the University of Western Australia and a Masters Degree in Strategic and Defence Studies from the Australian National University. He is married with 2 children. Greg has studied Indonesian and Tok Pisin.