Prior to his election as bishop, John functioned as provost of
cathedral chapter of Zagreb. Sometime after November 1287, when his predecessor
Anthony died, John was elected Bishop of Zagreb. He is first mentioned in this capacity in 1288. According to Antun Nekić, it is plausible he was candidate of the local clergy during the election. The historian considers his candidacy, because of their frequent cooperation in the upcoming years, was supported by the powerful
Babonić family, who began to extend their influence to the territory of
Lower Slavonia in those years, and even took control over the
Cistercian monastery of
Topusko. Otherwise it is also possible that John's election was conducted by the chapter independently of all spheres of national or regional powers. In this case, John's open collaboration with the Babonići may have been a consequence of his realization of his weekly situation and the need for local elites to protect his diocese and its possessions effectively. Earlier historiography, for instance the works of
Baltazar Adam Krčelić, incorrectly claimed that John, being as partisan of the
Capetian House of Anjou (claimants to the Hungarian–Croatian throne), was constantly embroiled in conflict with the cathedral chapter, which supported King
Andrew III of Hungary. However, this assumption is not confirmed by contemporary sources. Referring to the 14th-century John, the Archdeacon of Gorica as his source, Krčelić claimed that Bishop John usurped and confiscated church
benefices from the chapter. However, the chronicler makes no such mention, he simply notes that during the time of John there were many losses to the church and to the chapter itself. John was among those prelates, who participated in Andrew's campaign against the
Duchy of Austria in the summer of 1291. He was present, when the Hungarian and Austrian delegations concluded a truce at
Pressburg in late August 1291. During his episcopate, John maintained a close relationship with the Babonići through their
familiaris Grdun (or Gárdony), a distinguished nobleman in Slavonia from a
namesake kindred. The first appearance of their cooperation occurred in 1289, when John complained that Ugrin, the castellan of Garić or Garics (Podgaric) plundered church estates, including
Čazma. Grdun lent sum of 30 silver
marks to the bishopric in exchange for certain lands. By the next year (1290), Grdun entered the service of John, when he was mentioned as castellan of
Medvedgrad and
Blaguša (Blagosa), both episcopal castles. In June 1291, Grdun handed over Medvedgrad to Andrew III. Bishop John, who appears to have been in constant financial difficulties, was unable to formulate an advocacy policy at the royal court and was gradually subordinated to the private interests of the local oligarchs. For instance, he also lost the estate
Hrastovica in favor of
Radoslav Babonić during a lawsuit in September 1292. John was also forced to hand over large portions in church estates of
Vaška, Gvešće and Lubena to local nobles as
church prediales. According to historian Antun Nekić, John's episcopal activity was characterized by the gradual narrowing of the margin of maneuver; as a local clergyman, he could not develop a wide network among ecclesiastical circles. John died on 13 October 1295. ==References==