Ordained a priest in 1865, he taught moral theology in the seminary of Veroli, his diocese. After making his profession in the Congregation of the Most Holy Redeemer in 1878, he was appointed master of novices and taught dogmatic theology to students in the Roman province. From 1890 to 1922 he held the post of postulator general of his congregation, working successfully on the causes of St. Gerardo Maiella, St. Clement Hofbauer, B. Antonio Gianelli, Gennaro Sarnelli, Giovanni Nepomuceno Neumann, and other Ligurian religious such as Cesare Sportelli, Paolo Cafaro, Domenico Blasucci, Armando Passerat. He was also a consultant to the Apostolic Signatura and to the Congregations of Rites and Bishops and Regulars (confirmed in 1908 for that of Religious), within which he contributed to the drafting of the apostolic constitution Conditae a Christo. He played an important part in the preparatory works of the Code of Canon Law.
As he himself affirms, Father Benedetti first met Don Guanella by reputation, following as a consultant the various requests presented for the approval of Guanellian institutes. The personal acquaintance must have taken place after March 3, 1907, when don Guanella, at the suggestion of card. *Domenico Ferrata, asked the Redemptorist religious to "lend himself to giving a pious institute address in accordance with the rules" of his congregations. Don Guanella often referred to the advice of Father Benedetti, above all for questions relating to the moral direction of the institutes. Compilation of the rules, canonical and economic arrangement of the congregations, separation between men and women religious in the institutes, instruction of the information processes on the life and virtues of Caterina Guanella and Sister Chiara Bosatta, were some of the areas in which Don Guanella was led by the hand of experience of the Redemptorist father who in turn became "a fond friend and precious admirer" of Don Guanella.
