Late medieval origins. In the vows of Fernán González the town appears under the name of Arnietello. By donation from Alfonso VIII, it belonged to the bishops of Calahorra, after that the bishops of Calahorra were given the title Lords of Arnedillo. When in 1366 Enrique de Trastamara proclaimed himself king of castile in Calahorra, he gave the town to Juan Ramírez de Arellano.