The NA is a unique organisation that has continued to expand in response to its ever dynamic mandate, growing from a force of six battalions before the civil war to five divisions with combat support and combat service support arms. It has also transformed from a foot infantry army to one that now has mixed mechanized, motorized, amphibious and airborne combat formations units. The Army Headquarters (AHQ) is structured as follows:

Office of the Chief of Army Staff.

The office of the Chief of Army Staff (COAS) is at the apex of the NA structure. It exists under his command, to deter all forms of aggression and render MACA and MACP. Section 18(3) of the Armed Forces Act CAP A20 Laws of the Federation of Nigeria 2004, saddles the COAS with the responsibility of command, direction and general superintendence of the Army.

Department of Army Policy and Plans.

The Department of Army Policy and Plans (DAPP) is at the centre of General Staff activities of the Army Headquarter (AHQ). DAPP is both the “think tank” and the coordinator of all AHQ principal staff departments. At the head of the department is the Chief of Policy and plans (Army) (COPP (A)).

Department of Army Operations.

The Department of Army Operations (DAOPs) is the hub of all operations and training activities within the NA. It is responsible for the planning of training and directing of military operations by continuous assessment and evaluation of possible threat areas in the context of the overall National Defence Policy. The Department is headed by the Chief of Operations (Army) (COPs (A)).

Department of Army Administration.

The Department of Army Administration deals with the administration, welfare, discipline, employment and development of all human resources in the NA. The head of this Department is the Chief of Administration (COA(A).

Department of Army Logistics.

The Department of Logistics is responsible for all NA logistics matters. The Department also supervises all quartering services in the NA. The Chief of Logistics (Army) (COLOG (A)) heads the Logistics Department.

Department of Army Standards and Evaluation.

The Department of Army Standards and Evaluation (DASE) is responsible for making impartial and objective inquiries into the combat readiness, discipline, efficiency, economy, morale, training and safety measures throughout the NA. The Chief of Army Standards and Evaluation (CASE) heads the department.

Department of Military Secretary (Army).

The Department of Military Secretary is responsible for commissions, promotions, conversion, appointments, inter-corps transfer, extension of service and retirements in accordance with the Terms and Conditions of Service (TACOS) for NA Officers as may directed by the COAS or the Army Council.  The head of the department is the Military Secretary (Amy) (MS (A)).

Army Headquarters Garrison.

The Army headquarters Garrison (AHQ GAR) is responsible for the overall administration of AHQ and its Directorates in Abuja and Lagos areas. Its also coordinates all AHQ training activities. It is headed by Commander AHQ Gar.