He was ordained to the priesthood on 27 September 1872 by Cardinal Giuseppe Luigi Trevisanato, then Patriarch of Venice. After his ordination he did pastoral work in Venice, and also worked in the offices of the patriarchal curia.
Episcopate
Pope Pius X, Patriarch of Venice until his election as Pope, soon appointed Cavallari titular bishop of Philadelphia, and auxiliary bishop of Venice on 22 August 1903 and had him consecrated the next day in Rome by Cardinal Francesco Satolli. While the search for a new Patriarch was ongoing, Cavallari was named vicar general of Venice in January 1904. He exercised these offices until he himself was promoted to the patriarchal see of Venice on 15 April 1904 to fill the vacancy left by the election of Pius X.[3]