[1] Riario was consecrated as a bishop in the Sistine Chapel on 24 August 1572 by Cardinal Benedetto Lomellini assisted by Antonio Elio, Titular Patriarch of Jerusalem, and Giovanni Ambrosio Fieschi, Bishop of Savona.
[1] Pope Gregory XIII made him a cardinal priest in the consistory of 21 February 1578.
[1][2] He received the red hat and the titular church of Santa Maria in Aracoeli on 3 March 1578.
[1] Along with Cardinal Francesco Crasso and other prelates, he was charged with reforming the Roman Curia.
[1] He participated in the papal conclave of 1585 that elected Pope Sixtus V.[1] He died in Rome on 18 July 1585.