Attested in the sources between 1342 and 1372/1373. He appears as κῦρ and οἰκεῖος of the Byzantine Emperor Ioannes V Palaiologos and of the Serbian Emperor Stefan Uroš IV Dušan in the sources. He held the position of the Megas Hetaireiarches in 1348. According to the Praktikon issued in January 1342 by Michal Papylas Romanos was Ioannes Margarites the recipient of a confiscated land from Arsenios Tzamplakon located between Serres and Zichna and of a zeugelateion, which belonged to Kantakuzenos, near Zichna. He became these estates with the revenue of 55 hyperpyra and was fully exempted from paying taxes (κῦρ Ἰωάννην τὸν Μαργαρίτην ἀπὸ τῆς περὶ τὰ Ζίχνα καὶ τὰς Σέῤῥας ἀφαιρεθείσης ἀρτίως οἰκονομίας παρὰ τοῦ Τζαμπλάκωνος κυροῦ Ἀρσενίου, ἔτι δὲ καὶ ἀπὸ τοῦ περὶ τὰ Ζίχνα διακειμένου ζευγηλατείου τοῦ Καντακουζηνοῦ, ποσότητα ὑπερπύρων πεντήκοντα πέντε, καὶ κατέχῃ καὶ νέμηται ταύτην ἐλευθέραν πάντη καὶ ἀκαταδούλωτον). The possession of Ioannes Margarites at Kato Uska and Rachoba was declared exempt from the 9 nomismata tax and hereditary by the prostagma of the Byzantine Emperor Ioannes V. Palaiologos from October 1342. The former estates of Tzako [...], most probably Arsenios Tzamplakos, consisted of arable land and vineyards (Ἐπεὶ ὁ οἰκεῖος τῆ βασιλεία μου ὁ Μαργαρίτης κέκτηται δι’ ἀπογραφικῶν ἀποδείξεων τοῦ τε οἰκείου τῆς βασιλείας μου μεγάλου χαρτουλαρίου κυροῦ Ἰωάννου τοῦ Βατάτζη, καὶ τοῦ πανσεβάστου σεβαστοῦ οἰκείου τῆ βασιλεία μου ὀρφανοτρόφου κυροῦ Κωνσταντίνου [ ] εἴς τε τὸ χωρίον τὴν Κάτω Οὔσκαν καὶ τὴν Ῥάχοβαν ἀπό τε Τζάκω[ ] ὑποστάσεων καὶ δημοσιακῶν γῆν τινα καὶ ἀμπέλια). Ioannes Margarites granted his land at Kato Uska to the Monastery of Saint John Prodromos near Serres. The Serbian King Stefan Uroš IV Dušan confirmed the gift of Ioannes Margarites in the chrysobull charter, which was issued in October 1345. The Serbian Emperor Stefan Uroš IV Dušan confirmed the endowment of Ioannes Margarites to the Batopedi Monastery in April 1348. It consisted of a property near the village Dratzoba, land in the vicinity of Mikra Neboliane, a property in the town of Kaisaropolis, a piece of land not far from the town Chrysupolis, house and a church in the town Chrysopolis (ὁ οἰκεῖος τῆ βασιλεία μου μέγας εταιρειάρχῃς κῦρ Ἰωάννης ὁ Μαργαρίτης δι’ τῆς βασιλείας μου ὅσον ἐκέκτητο περὶ Δράτζοβαν τὸ χωρίον καὶ γῆν εἰς τὴν Μικρὰν Νεβόλιανιν καὶ ὅσον εἶχεν εἰς τὴν Καισσαρόπολιν ἅτινα προκατεῖχε διὰ χρυσοβούλλου τῆς βασιλείας μου, ἀλλὰ δὴ καὶ τὴν εἰς τὴν Χρυσούπολιν γῆν αὐτοῦ, καὶ ἐντὸς τοῦ κάστρου ἐκκλησίαν καὶ ὀσπήτιν). He became a monk in the Monastery of Saint John Prodromos near Serres. He probably requested a firman from the Ottoman Sultan. The Monastery of Saint John Prodromos near Serres obtained the charter from Ottoman Sultan Murad I in 1372/1373. The monastery is mentioned in the charter as the church of Margaritis.