He was the son of Eutropius, a prominent senator, and Theodora, who lived in Constantinople. At the age of twelve, he secretly fled his home, taking nothing but a Gospel book with him. Entering the Monastery of the Unsleeping Ones in the City, he gave himself up with fervor to a life of prayer, self-denial and obedience. For three years he ate only on Sundays after taking communion, and became so thin and haggard that he bore no resemblance to the young nobleman who had entered the monastery.

Tormented by longing to see his parents, but unwilling to give up the ascetic struggle, he left the monastery with his Abbot's blessing, dressed in beggar's rags, and took up residence in a poor hut near the gate of his parents' house. Here he lived, mocked by those who had once been his servants and despised by his own parents, who no longer recognized him.

After three years, Christ appeared to him and told him that his end was drawing near, and that in three days angels would come to take him home. John sent a message to his parents, asking them to visit his hut. In perplexity, they came, and John, showing them the Gospel book that they had given him as a child, revealed to them that he was their son, and that he was about to die. They embraced him, rejoicing at their reunion but weeping for his departure from this life. Immediately, he gave back his soul to God.

The whole City of Constantinople was stirred by the story, and great crowds came to John's burial service. A church was later built on the site of his hut, and many miracles were wrought there through the Saint's prayers.