A hagiography of Theodosius was written in the twelfth century. According to the Primary Chronicle:
His main feast day is May 3, the date of his repose. His relics were discovered by Saint Nestor the Chronicler, on August 14, 1091, and were found to be incorrupt.
The relics were transferred to the main catholicon (cathedral) of the monastery, and a second annual feast day was established in commemoration of this event.