Montanari was born in Sertãozinho, São Paulo state inside the territory of the archdiocese of Ribeirão Preto.

While in Rome, he lived at the Pontifício Colégio Pio Brasileiro [pt] He was ordained a priest for the Roman Catholic Archdiocese of Ribeirão Preto on 18 August 1989.

After his ordination he was appointed pastor and a year later was professor of theology in Ribeirão Preto and at the same time the seminary of Uberaba until 1994.

[2] He returned to Rome in 2002 to study at the Pontifical Gregorian University, where he obtained his license in dogmatic theology in 2004.

On 12 October 2013 Montanari was appointed Titular Archbishop of Capocilla and secretary of the Congregation for Bishops.