Gregory XV was also responsible for the canonization of Saints Ignatius of Loyola, Francis Xavier, Teresa of Ávila, and Philip Neri, which solidified his commitment to the Counter-Reformation.

On 12 March 1612, Pope Paul V appointed him as the Archbishop of Bologna, for which he was presumably ordained to the priesthood and then he was consecrated a bishop on 1 May of that year in the church of Sant'Andrea al Quirinale in Rome.

He was crowned on 14 February 1621 by the protodeacon, Cardinal Andrea Baroni Peretti Montalto, and assumed possession of the Basilica of Saint John Lateran on 14 May 1621.

At the moment of his election, chiefly through the influence of Cardinal Scipione Borghese, at his advanced age (he was 67) and with his weak state of health he saw at once that he would need an energetic man, in whom he could place implicit confidence, to assist him in the government of the Church.

The Catholic Encyclopedia allows that "Ludovico, it is true, advanced the interests of his family in every possible way, but he also used his brilliant talents and his great influence for the welfare of the Church, and was sincerely devoted to the pope".

Gregory XV interfered little in European politics, beyond assisting Ferdinand II, Holy Roman Emperor, and the Catholic League against the Protestants,[1] to the tune of a million gold ducats,[citation needed] and Sigismund III Vasa, King of the Polish–Lithuanian Commonwealth, against the Ottoman Empire.

On 12 March 1622, the pope canonized several saints: Francis Xavier, Ignatius of Loyola,[1] Isidore the Laborer, Philip Neri and Teresa of Ávila.