 After a period of pastoral work in Rome, Tor di Mezzavia d'Albano, and Torretta Massimi, Roberti was Vice-Rector of the Pontifical Minor Seminary in Rome from 1915 to 1916.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.Made an advocate of the Roman Rota and the Holy Office in 1927, Roberti became a referendary prelate of the Apostolic Signatura on 17 March 1928, and later a voting prelate of the same on 27 November 1930.