Sandri was born in Buenos Aires to Antonio Enrico Sandri and Nella Righi, who had emigrated to Argentina from Ala, a village in Trentino in Italy. He studied humanities, philosophy and theology at the Metropolitan Seminary of Buenos Aires, and earned a Licentiate in Theology from the Pontifical Catholic University of Argentina. On 2 December 1967 he was ordained to the priesthood by Archbishop Juan Carlos Aramburu and became his secretary.
