Aráoz assisted Manuel Belgrano in the Army of the North. He was elected by Tucumán to the Congress and served in 1816 for the declaration. After the Congress moved to Buenos Aires, he resigned his mandate and returned to his hometown. He collaborated in local politics with his close relative, Bernabé Aráoz, assisting in the 1820 formation of the Republic of Tucumán and serving as a legislator in the provincial assembly. He wrote the Republic's constitution and was the editor of the first provincial newspaper. After the death of Bernabé and the collapse of the Tucumán Republic, Aráoz played no further part in politics.