He was raised to the rank of domestic prelate of his holiness on 2 March 1917, and taught canon law at his alma mater of the Pontifical Roman Athenaeum S. Apollinare from 1918 to 1938.

He was named secretary of the Sacred Congregation of the Council on 9 March 1946; as such, he was the second-highest official of that dicastery, successively under Cardinals Francesco Marmaggi, Giuseppe Bruno, and Pietro Ciriaci.

In 1948, after a communist newspaper accused him of illegal financial manipulations, Roberti successfully sued for libel, sending the reporter to jail for twenty months.

Pope John XXIII created him Cardinal-Deacon of Santa Maria in Cosmedin in the consistory of 15 December 1958, and then prefect of the Apostolic Signatura on 14 November 1959.

[3] Before resigning as prefect of the Apostolic Signatura on 24 March 1969, Roberti exercised his right as a cardinal-deacon of ten years' standing to become a cardinal priest, receiving the titular church of Ss.