Born in Genzano, Luigi Jacobini studied at the seminary in Albano before being ordained to the priesthood in Rome on September 23, 1854. He then furthered his studies at the Sapienza University in Rome, where he obtained his doctorate in theology (July 20, 1857) and his doctorate in civil and canon law (June 25, 1858). Jacobini then entered the Roman Curia, serving as a staff member in the Secretariat of Ecclesiastical Affairs. He was raised to the rank of Domestic Prelate of His Holiness, and also became Secretary of the Congregations of Propaganda Fide, which at that times also was responsible for relations with Oriental Rites.