Earlier historiography incorrectly considered that James studied at the Abbey of St Genevieve in Paris, misspelling Job's name to Jacobus (James).
James entered the service of Duke Andrew, who – opposing his brother Emeric's reign – established a sovereign rule in Croatia and Dalmatia at the turn of the 12th and 13th centuries. Beside his position of provost of Zagreb, James functioned as chancellor of the ducal court from 1200 to 1202, when Emeric was forced to acknowledge his brother's territorial claims. Because of his titles "magister ducius et cancellarius" and "prepositi magistri nostri et cancellarii", there are assumptions that James was one of the tutors of the young Andrew prior to that. James was made provost of Kalocsa by 1211. In this capacity, he assisted the work of Archbishop Berthold (King Andrew's brother-in-law) who had "incomplete knowledge". Thereafter, he served as vicar of the elderly Boleslaus, Bishop of Vác.
James was elected bishop of Vác in 1213, succeeding Boleslaus. In May 1218, Pope Honorius III launched an investigation against James, who, according to the accusations, lived a luxurious life, neglected the duties of his office, irresponsibly managed the bishopric's assets and allowed the buildings of the diocese to fall into disrepair. James allegedly did not shy away from violence when he harmed the priests and abused the censure of excommunication against his critics. Pope Honorius ordered Bishop Robert of Veszprém and the abbots of Zirc and Pilis to investigate the accusations. Although the outcome of the investigation is unknown, James held the bishopric until his death in 1221.