On 5 May 1913, Pompili was appointed Titular Archbishop of Philippi. He received his episcopal consecration on the following 11 May from Cardinal Antonio Agliardi, with Archbishop Donato Sbarretti and Bishop Americo Bevilacqua serving as co-consecrators, in the church of S. Vincenzo de' Paoli alla Bocca della Verità. In late May 1914, Pompili opted to become a cardinal-priest, with the title of Santa Maria in Aracoeli. He then participated in the conclave of 1914, which elected Pope Benedict XV, and was named archpriest of the Lateran Basilica on 28 October 1914.