The National Army of Colombia (Spanish: Ejército Nacional de Colombia) is the land warfare service branch of the Military Forces of Colombia. With over 361,420 active personnel as of 2020, it is the largest and oldest service branch in Colombia, and the third largest army in the Americas after Brazil and the United States.

It is headed by the Commander of the National Army (Comandante del Ejército Nacional), falls under the authority of the General Commander of the Military Forces (Comandante General de las Fuerzas Militares), and is supervised by the Ministry of National Defense, which answers to the President of Colombia.

The modern Colombian Army has its roots in the Army of the Commoners (Ejército de los Comuneros), which was formed on 7 August 1819 – before the establishment of the present day Colombia – to meet the demands of the Revolutionary War against the Spanish Empire. After their triumph against the Spanish, the Army of the Commoners disbanded, and the Congress of Angostura created the Gran Colombian Army to replace it. Throughout its history, the Colombian Army has seen action in several wars and civil conflicts, including the Gran Colombia-Peru War, the Ecuadorian–Colombian War, the Thousand Days War, and the Korean War. Since the mid-1960s, the Colombian Army has been involved in a low-intensity asymmetrical war known as the Colombian Armed Conflict.