The Army of Arauco (Spanish: Ejército de Arauco) was a professional army in the service of the kings of Spain that was based in Spanish-Mapuche frontier, south-central Chile, during the 16th to 19th centuries.

The army was established after the disastrous Destruction of the Seven Cities (1598–1604) to fight in the Arauco War against anti-Spanish Mapuche coalitions.

The army was financed by silver from Potosí, in a payment called Real Situado.

[2] The Army of Arauco shaped the economy of southern Chile as it created a demand for wine and it meant an inflow of silver.

In addition Guaraní indians serving the army are thought to have helped establish the custom of drinking yerba mate in southern Chile.