[1] It is presumable that he came to Hungary, when became a royal tutor of King Andrew's eldest son Béla (born 1206), replacing Bernard of Perugia, Archbishop of Split.

That sentence reflects Robert's knowledge of Novellae Constitutiones (one of the four parts of the Roman law), where the same phrase appears regarding the donations of the churches.

[6] Robert and his fellow bishop Peter of Győr were entrusted in 1211 to prepare a convention draft and submit to the Roman Curia on the subject of conflicts of jurisdiction between the archdioceses of Esztergom and Kalocsa.

In response, Robert sent a complaint to Pope Innocent III, because the coronation of the queens consort in Hungary had been traditionally the privilege of his see, according to his narration.

After Robert's personal visit in Rome, the pope sent two legates, cardinals Pelagio Galvani and Stefano di Ceccano to Hungary in order to investigate the complaint and confirmed the privilege of the See of Veszprém in April 1216.

In February 1217, Pope Honorius authorized him to absolve those noblemen from their vow, who were entrusted with protection of the realm, while Andrew II prepared for the crusade.

The Holy See ruled in favour of Uros in 1215; despite the verdict, Robert tried to take advantage of the abbot's absentee, who participated in the Fifth Crusade, and forced the concerned churches to pay tithes to the Diocese of Veszprém in 1217–1218.

Historian Nora Berend considers Robert, still as Bishop of Veszprém, was behind the charges, anticipating his future leading role on the issue.

Two rival factions emerged in the following months: a part of the canons nominated Desiderius of Csanád, while other members of the college supported James of Nyitra (or Nitra).

But, instead, he had to postpone his intention of travel to the Holy Land;[8] the nearly contemporaneous Alberic of Trois-Fontaines recorded that a Cuman chieftain's son visited Robert in 1227, asking the archbishop to baptize him together with his 12 retainers.

[20][21] Pope Gregory IX expressed his joy over the missionaries' success in "Cumania" and in the neighboring "land of the Brodnici" in a letter to Robert on 31 July 1227.

[15][25] Pope Gregory confirmed the consecration and urged the head of the Hungarian Dominicans to send new missionaries to the Cumans, and praised Duke Béla who had decided to visit Cumania in the company of Archbishop Robert.

[26] In Cumania, Robert carried out his mandate of papal legate in the interest of the Holy See (as he contributed to the political, territorial and spiritual expansion of the Christian faith), neglecting the Hungarian monarch's need for take an active role.

The pope informed Robert on the situation of the Latin Empire in his letter in May 1231 and requested him to reach out to Andrew II to provide assistance to the crusader state as he had previously promised.

[31] The employment of Jews and Muslims to administer the royal revenues led Robert and the other subordinated prelates into conflict with King Andrew II.

[32] On 3 March 1231, Gregory authorized the archbishop (legate natus) to perform acts of religious censure to persuade Andrew to dismiss his non-Christian officials.

[33][34] The document emphasizes specifically coinage among the public offices forbidden to non-Christians (Jews and Muslims), as the royal mint was located in Esztergom and was part of the privileges of its archbishop.

Robert excommunicated Palatine Denis, son of Ampud and other royal advisors (e.g. Master of the treasury Nicholas[35] and a certain chamberlain Samuel of "Saracen" origin) and put Hungary under an interdict on 25 February 1232,[15] because the employment of Jews and Muslims continued despite the Golden Bull of 1231.

[36] Berend says Robert bemoaned the situation of the Catholic Church in the realm, as several clergymen lost their offices due to the presence of non-Christian financial experts.

The pope emphasized that Robert's jurisdiction as papal legate was limited only to the area inhabited by the Cumans and ordered him not to apply further ecclesiastical punishments.

[38] For the remaining time, their relationship improved; when the elderly Andrew, who had been widowed, married the 23-year-old Beatrice D'Este on 14 May 1234, Robert crowned the new queen (as archbishop, despite his former protests as Bishop of Veszprém against John of Esztergom), even though the king's sons – his protege Béla and Coloman – were sharply opposed to the marriage.

[40] When papal legate Giacomo di Pecorari arrived to Hungary in 1233, he also dealt with the issue, but the protocol was lost and the canonization process postponed.

However royal churches did not recognize his jurisdiction; for instance, Pope Gregory excommunicated Albert, provost of Arad in 1235, because he refused to acknowledge the authority of the archbishop.

[42] Historian Géza Érszegi considers both documents as forgery, as a royal charter issued in 1243 confirms Béla granted the church to the Bélakút Abbey in that year.

[43] On 29 September 1239, a month before Robert's death, Béla gave permission to the archdiocese to build Víziváros (Latin: Civitas Archiepiscopalis, a neighborhood of Esztergom), under the royal castle and the St. Adalbert Basilica.