Following the death of Patr. Yuḥanon IX (1057), Yuḥanon was elected by the Oriental bps. and consecrated in Amid, while simultaneously a different candidate was elected and consecrated with broader support (Athanasios VI Ḥoye). Yuḥanon subsequently stepped down and opted for a quiet life of study and scholarship, thus allowing Athanasios to take office. When five years later, however, Athanasios died, Yuḥanon was urged to come back and was unanimously elected as Athanasios’s successor, serving for nine years, until his death in 1072 (or 1073). Yuḥanon spent most of his life in Amid, rather than in Melitene, due to the Byzantine oppression of the Syr. Orth. Our main sources for Yuḥanon’s life are Michael Rabo (XV.1; ed. Chabot, 573–5 and 579 [Syr.]; vol.  3, 162–4 and 170–2 [FT]) and Bar ʿEbroyo (Ecclesiastical History, ed. Abbeloos and Lamy, vol. 1, 435–48).

According to Michael Rabo, Yuḥanon was a very prolific writer, who ‘filled the universe with his letters and volumes’ (XV.3: ed. Chabot, 579 [Syr.]; vol. 3, 171 [FT]; cf. Bar ʿEbroyo, vol. 1, 447). He specifically mentions his work on Ephrem and Isḥaq (of Antioch): Yuḥanon is said to have brought (selections from) their work together in one volume, which he wrote in his old age with his own hands, prevented by death, however, from finishing it. Yuḥanon’s name is in fact associated with Isḥaq’s memre in ms. Vat. Syr. 119 (cf. S. E. and J. S. Assemani, Bibliothecae Apostolicae Vaticanae … Catalogus, I.3 [1759], 115–23) and in ms. Berlin 56 (cf. E. Sachau, Verzeichniss der syrischen Handschriften, 188–90). A letter addressed to the Cath. of the Armenians, in which Armenian criticism against the Syr. Orth. is refuted and certain views and practices of the latter are defended, is transmitted as the first part of a larger compilation dealing with the Armenians. It was edited, translated, and studied twice in 1912 by two scholars working independently of one another. There is also an Anaphora transmitted under Yuḥanon’s name. Michael reports that Yuḥanon wrote 4 books (of poetry) on the sack of Melitene (by the Turks in 1058), but these have not been preserved (Chabot 574; vol. 3, 159).

In Arabic a letter to the Coptic Patr. Christodoulos (1047–77), defending the Syr. Orth. practice of mixing salt and oil with the Eucharistic bread, survives. In addition, P. Sbath reports that a treatise on the unity and trinity of God, against the Muslims, exists in one of the mss. of his collection (see Graf).