Born in Porto, Nunes Barreto completed his studies in Salamanca and served as parish priest in the archdiocese of Braga. In 1545 he entered the Society of Jesus in Coimbra.

Born in Porto, Nunes Barreto completed his studies in Salamanca and served as parish priest in the archdiocese of Braga. In 1545 he entered the Society of Jesus in Coimbra.