Like his predecessor, Clement V, Pope John centralized power and income in the Papacy and lived a princely life in Avignon.

John opposed the policies of Louis IV the Bavarian as Holy Roman Emperor, which prompted Louis to invade Italy and set up an antipope, Nicholas V. John also opposed the Franciscan understanding of the poverty of Christ and his apostles, promulgating multiple papal bulls to enforce his views.

[10] John was known to have a temper, and involved himself in the politics and religious movements of many European countries in order to advance the interests of the papacy.

[24] In preparation of this, the cardinal legate, Bertrand du Pouget, had been working for years in Bologna to oversee the construction of a papal palace and to integrate the political climate for the papacy's arrival.

[29] John promoted William FitzJohn, bishop of Ossory to the bishopric of Cashel, while Alexander Bicknor, a personal recommendation of Edward, was given Dublin.

[34] By November 1317, Guillelmo de Tocco, Prior of the Benevento Dominican monastery, was heading a preliminary investigation into Thomas Aquinas' sainthood.

[35] In the summer of 1318, John met with de Tocco, who presented letters from the regal heads of Sicily imploring for a papal inquiry into the sainthood of Aquinas.

[36] John then issued two letters, nominating as papal commissioners: Umberto, Archbishop of Naples; Angelo, Bishop of Viterbo; and Pandulpho de Sabbello, who was unable to attend.

[37] The commission sent finalized documents to the Papal Curia and John XXII canonized Thomas Aquinas formally on 18 July 1323.

[38] Prior to John XXII's election, a contest had begun for the Holy Roman Empire's crown between Louis IV the Bavarian and Frederick I of Austria.

[40] In response, in April 1317, John imposed a new concept, vacante imperio, granting the power to administer the empire to the pope,[41] which was contained within the papal bull Si fratrum.

[42] By 1322, faced with a growing Ghibelline movement in northern Italy, John had instructed his papal legate, Bertrand du Poujet, to call for a crusade against Milan.

[51] Following Louis's coronation of Nicholas V, Franciscan Minister General Michael Cesena, Bonagrazia Bergamo, and William of Ockham all fled Avignon.

[56] On 26 March 1322, with the bull Quia nonnunquam, he removed the ban on discussion of Exiit qui seminat,[57] and commissioned experts to examine the idea of poverty based on belief that Christ and the apostles owned nothing.

The Franciscan chapter held in Perugia in June 1322 responded with two encyclicals stating that all judgments made by the Roman Church were to be regarded as final and could not be revoked if they were not erroneous.

On 12 November 1323, he issued the bull Quum inter nonnullos, which declared "erroneous and heretical" the doctrine that Christ and his apostles had no possessions whatsoever.

[59][60] Influential members of the order protested, such as the minister general Michael of Cesena, the English provincial William of Ockham, and Bonagratia of Bergamo.

In January 1334, in complete opposition to John XXII, the Faculty of Theology of the Sorbonne stated that after death the blessed souls are raised to the beatific vision.

[64] Louis, sensing an opportunity to remove him, conspired with cardinal Napoleone Orsini to depose John at an ecumenical council.

[28] John, considered by many to be theologically incompetent,[65] backed down from his position on the day before his death, agreeing that those who die in grace do indeed immediately enjoy the beatific vision.

Kors points to the fact that Pope John had been the victim of an assassination attempt via poisoning and sorcery as a personal factor behind this change.

Although this was the official ruling for the church, Pope John's first order dealing with magic being tried by the Inquisition was in a letter written in 1320 by Cardinal William of Santa Sabina.