The Pakistan Army (Urdu: پاکستان بری فوج‎) is the principal land warfare branch of the Pakistan Armed Forces. The roots of its modern existence trace back to the British Indian Army that ceased to exist following the partition of British India, resulting in the parliamentary act that established the independence of Pakistan from the United Kingdom on 14 August 1947. According to the estimation provided by the International Institute for Strategic Studies (IISS) in 2017, the Pakistan Army had approximately 650,000 active-duty personnel, supported by the Army Reserve and National Guard effectively making it the 6th largest army in the world in terms of manpower. Citizens can enlist for voluntary military service upon reaching 16 years of age and cannot be deployed for combat until age 18 in accordance with the Constitution of Pakistan.

The Pakistan Army’s primary objective and constitutional mission is to ensure the national security and national unity of Pakistan by defending it against external aggression or the threat of war. It can also be requisitioned by the federal government to respond to internal threats by maintaining peace and security within its land borders. During events of national and international calamities and emergencies, it conducts humanitarian rescue operations at home and is an active participant in peacekeeping missions mandated by the United Nations (UN), most notably playing a major role in rescuing trapped American soldiers requesting for a quick reaction force (QRF) during Operation Gothic Serpent in Somalia. Troops from the Pakistan Army also had a relatively strong presence as part of a larger UN coalition during the Bosnian War and greater Yugoslav Wars.

The Pakistan Army, which is a major component of the Pakistani military alongside the Pakistan Navy and Pakistan Air Force, is a volunteer force which has seen extensive combat during three major wars with neighbouring India and several border skirmishes on its porous border with Afghanistan. Since the 1960s, elements of the army have been repeatedly deployed to act in an advisory capacity in the Arab states during the events of the Arab–Israeli wars as well as to aid the U.S.-led coalition against Iraq in the Gulf War. Other notable military operations during the global War on Terror in the 21st century included: Zarb-e-Azb, Black Thunderstorm and Rah-e-Nijat.

The Pakistan Army has a regimental system but is operationally and geographically divided into command zones, with basic field of being the corps. The Constitution of Pakistan mandates the role of the President of Pakistan as the civilian Commander-in-Chief of the Pakistani military.
The Pakistan Army is commanded by the Chief of Army Staff, who is by statute a four-star ranking general and a senior member of the Joint Chiefs of Staff Committee appointed by the Prime Minister of Pakistan and subsequently affirmed by the President of Pakistan. The current Chief of Army Staff of the Pakistan Army is General Qamar Javed Bajwa, who was appointed to the position on 29 November 2016.