The purpose of the publication is to introduce into scientific circulation documents that reveal and supplement, in a new way, the evidence about the life and work of the Ukrainian ascetic, church and cultural figure and Saint Job (Ezekiel) Kniahynycky (ca. 1550–1621), in particular, about the Athos period of his biography and foreign travels as part of the embassies of the Vatopedi Monastery. The methodological foundations of the study are based on the principles of historicism, scientific objectivity, systematicity, and a dialectical approach to historical phenomena. In accordance with the goal and objectives, a combination of general scientific, interdisciplinary, and special research methods was used. The scientific novelty lies in the fact that for the first time the documents from the case of the arrival of the delegation of the Vatopedi Monastery from the territory of the Polish-Lithuanian Commonwealth to Smolensk in 1592, consisting of the ecclesiarch and elder Gerasimus, and the monks Ezekiel and Jonikiy, were introduced into scientific circulation. Based on the analysis of the entries in these documents, as well as the analysis of the 1596 marks in the manuscript Slavic Gospel-tetra from the library of the Vatopedi Monastery (Slavic 1), it is established that the monk Ezekiel of Vatopedi mentioned in them is the same Ezekiel Kniahynytsky, who later took the monastic vows with the name Job and contributed to the revival and reform of Orthodox monasticism in the western Ukrainian lands. It is emphasised that the document confirms the authenticity of the record in the life of Job Knyahynytsky, written after his death by his disciple Ignatii of Liubarov. The analysis of the entries in these documents, as well as the notes in the late 14th-century manuscript Slavic Gospeltetra, which is kept in the library of Vatopedi, allows us to more accurately date the time of Knyahynytsky’s stay in the Vatopedi monastery. It is established that another monk, Sava, lived there with him. The author suggests that another well-known Ukrainian church and cultural figure and polemic writer, St John Vyshensky, may have stayed with them for some time at the Vatopedi Monastery. It is noted that at the end of the 16th century, a group of Ukrainian monks-scribes probably operated at the Vatopedi Monastery. Later on, the author observes the establishment of closer ties between the Vatopedi Monastery, and the Ukrainian Orthodox monasticism and the Cossacks.