Saint Dionysios was born in the village of Korissos, Kastoria, to pious parents who were farmers. At a young age, he went to Mount Athos near his brother Theodosios. Dionysios, with the help of his brother’s own teacher, learned to study the Holy Scriptures, and quickly became distinguished for his humble mind and his charitable character.
A few years later, Emperor Alexios Komnenos III (1350 - 1390), Theodosios became a Metropolitan in Trebizond. Dionysios was very pleased when he learned of this, first out of brotherly love, and second because now he could more easily carry out a plan of his own.
After his ordination to the priesthood, Saint Dionysios transferred his place of asceticism to the steep mountain of little Athos or Antiathos, the so-called Old Prodromos and the Panagia. Shortly thereafter, he wanted to build a church and a suitable monastery. That plan eventually succeeded by the grace of God. Thus, in 1375, Alexios III, through the intercession of his brother, Metropolitan Theodosios, approved the building of the Monastery of the honorable Forerunner and Baptist John. The emperor in Dionysios gave 50 somia (400,000 grosia), and then three thousand komninata for his work. Thus Saint Dionysios built the Monastery of the honorable Forerunner, which was known afterwards by the name given by her builder.
Saint Dionysius reposed in Trebizond, where he had gone to ask for further help from the emperor for the iconography of the monastery.