Gregorios 48 was hegoumenos of the monastery of Agauros; in 787 he attended the Second Council of Nikaia (the Seventh Ecumenical Council) and is attested at the fourth session, on 1 October 787, when he subscribed the statements read out from the Fathers in support of the veneration of icons: Mansi XIII 152 (Γρηγόριος ἡγούμενος Ἀγαύρου; the Latin version, at XIII 151, calls him "hegumenus Agauri)". He probably attended other sessions of the Council also; see Gregorios 45.

In c. 796 Gregorios 48 received a visit at the monastery of Agauroi (sic) near Prousa, of which he was head (τῷ αὐτῆς πατρὶ Γρηγορίῳ), from Ioannikios 2, who had decided to withdraw from the world and become a hermit; Gregorios 48 advised him to spend time in a coenobium to learn hymns and the order of service and other needful matters: Sabas, Vita Ioannicii 8, cf. Petrus, Vita Ioannicii 8 (τὸν τῆς μονῆς προεστῶτα; unnamed). When Ioannikios 2 subsequently returned to Agauroi, Gregorios 48 provided him with a cell in which to live: Sabas, Vita Ioannicii 10. Gregorios 48 ordered two of the monks at Agauroi, Eustratios 19 and Theophylaktos 105, to prepare the cell for Ioannikios 2: Petrus, Vita Ioannicii 10, Sabas, Vita Ioannicii 10, 14 (τὸν τῆς Ἀγαύρων καθηγεμόνα Γρηγόριον). It is not certain if these refer to one occasion when Ioannikios 2 returned or to more than one. Probably in 811 or 812 Gregorios 48 sent Eustratios 19 to Constantinople on business, where Eustratios 19 learned that Ioannikios 2 had foretold the deaths of the emperors Nikephoros 8 and Staurakios 2: Sabas, Vita Ioannicii 15. Staurakios 2 died in January 812. Gregorios 48 himself eventually died in Constantinople within days of completing some business for which he had gone there; prior to this visit he had sought out Ioannikios 2 to obtain his blessing before leaving and had been warned of his approaching death, but in riddling terms that he failed to understand; he was succeeded as hegoumenos first by his nephew, Anonymus 560, and then by Eustratios 19: Sabas, Vita Ioannicii 32, Petrus, Vita Ioannicii 59. The date of his death, to judge by its position in the narratives, was either in the reign of Michael II (Michael 10), perhaps c. 825 (see Ioannikios 2), or possibly in that of Theophilos 5. He was hegoumenos of the monastery of Agauroi near Prousa apparently from at least 787 to c. 825.

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