John V shepherded the Church five years and nine months according to the Leoglavius and the Nicephoros catalogues. Kallistos Nicephorus numbers four years and a few months, whereas Theophanes writes six years.
John was orthodox, as was his predecessor, Thomas II. Prior to his election to the Patriarchal Throne, he was a Presbyter of Constantinople, Protekdikos and Chartophylax of the Patriarchate, and Skevophylax of Saint Sophia.
The Orthodox Church celebrates his memory on the 18th of August.