On 27 March 1882, he acted as ablegatus in delivering the red galero to the newly created cardinal Joaquín Lluch y Garriga.

He was then named a canon of St. Peter's Basilica on 11 July 1889, Substitute (or deputy) of the Secretariat of Briefs on 18 March 1892, and both Domestic Prelate of His Holiness and Protonotary apostolic ad instar participantium two days later.

[1] Marini was highly active in pursuing greater unity between the Eastern Christianity and the Western Church.

Pope Benedict XV created him Cardinal-Deacon of Santa Maria in Domnica in the consistory of 4 December 1916.

During that same year, he participated in the papal conclave that selected Pope Pius XI, although he was suffering from acute influenza; The Times of London erroneously reported Marini's death.