Commission biblique pontificale
Pius X created him Cardinal Deacon of Santa Maria in Via Lata in the consistory of 27 November 1911. Billot was one of the cardinal electors in the conclave of 1914, and participated in conclave of 1922 as well. He was also one of the three Cardinal-Presidents of the Pontifical Academy "S. Tommaso" in Rome, together with Benedetto Lorenzelli and Michele Lega. He was appointed a member of the Pontifical Biblical Commission on 6 February 1923.