The Chief of Staff of the Defence Forces (COS) (Irish: Ceann Foirne na bhFórsaí Cosanta) is charged with the executive management of the Irish Defence Forces, and is the most senior military officer of the Army, Naval Service and Air Corps branches.

The Chief of Staff is appointed by the President of Ireland, who is the Supreme Commander of the Defence Forces, on the recommendation of the Minister for Defence subject to the approval of the Government of Ireland.

The office of the Chief of Staff consists of his personal staff, a strategic planning office, a public relations section and the military judge.

[1] The Defence Forces Chief of Staff sits on the government's National Security Committee (NSC).

The two brigade group structure envisages distinct operational areas of responsibility for each of the brigades and is supported in their responsibilities by the Naval Service and Air Corps.