The emergence of the Kilifarevo Monastery is closely connected with the name of Theodossius of Turnovo, an acknowledged Bulgarian Hesychast and man of letters. He settled in these parts towards 1348, a few years after the death of the famous Hesychast Gregory Sinait, whose monastery in Southern Strandzha he had inhabited before.
Accompanied by his disciple Romil of Vidin, after several years of roaming about Mount Athos and Eastern Bulgaria, St Theodossius finally found seclusion in the thick forests above the River Belitsa near the village of Kilifarevo. Gradually, more followers gathered round him and soon afterwards a monastery was raised at this place with the assistance of Tsar Ivan Alexander, which in no time turned into a significant literary center of 14th century Bulgaria, into a spiritual haven of Orthodox Hesychasm. All kinds of liturgical books, lives, homilies and secular chronicles were written and translated here. It was exactly at the Kilifarevo Cloister that the creative endeavours of Patriarch Euthymius and Romil of Vidin were first given an impulse, of the future Metropolitan Bishop of Kiev and Moscow Kyprian and of many other adherents. When the Ottoman invaders reached Turnovo towards the end of the mid – 14th century, the monastery was fortified with walls and fortress towers. Tsar Ivan Alexander personally donated funds for the construction of the chief tower and a new church.