The Monk Kornilli of Komel'sk was descended from the boyar (noble) family Kriukov. His brother Lukian served at the court of the Moscow GreatPrince. When Lukian, getting up in years, decided to set off to the monastery of the Monk Kirill of Beloezersk, there also followed after him Kornilii, who from a young age yearned after the solitary life. Having taken vows, the young Kornilii began his monastic exploits with a difficult obedience – he wore heavy chains in the bakery, and in his spare time of rest he occupied himself with the copying of church books. Because of his love for solitude, the Monk Kornilii later left the Beloezersk monastery, and he visited Rostov. At Novgorod Sainted Gennadii (Comm. 4 December) attempted to hold on to him, but the ascetic settled in a desolate spot not far from Novgorod. When people began to visit here also, yearning for the monastic life, he moved on to the Tver' Savvatiev wilderness monastery, and later in the year 1497, he settled in the Komel'sk forest, not far from Vologda, where he built himself a cell. To this place of the ascetic activity of the Monk Kornilii monks began to gather, and in 1501 he built a wooden church there in honour of the Entry into the Temple of the MostHoly Mother of God. And in that year Metropolitan Simon ordained him priest-monk. In 1512, when the number of brethren had grown, the monk constructed a stone church and he wrote down for the brethren an Ustav (Rule), compiled on the basis of the Ustavs of the Monks Joseph of Volotsk and Nil of Sorsk. This was the third Ustav, written by Russian saints for monastics. The Monk Kornilii of Komel'sk distinguished himself with liberality towards the unfortunate, and during a time of famine he constructed an orphanage for children on the monastery courtyard. For his love towards the poor and orphaned, the Monk Kornilii was many times granted graced vision of the Monk Anthony the Great (Comm. 17 January), for whom he had a especial reverence, and he raised up a church at his monastery in honour of the great ascetic. The strictness of life of the saint provoked some of the brethren to grumbling, and the Monk Kornilii was compelled to leave the monastery and he settled at Lake Sursk, 70 versts from his monastery. At times also he pursued asceticism at the Trinity-Sergiev Lavra. Interceding for the monks of the Korniliev monastery, GreatPrince Vasilii Ivanovich urged the monk to return to his own monastery. The ascetic gave in, and having returned to his own monastery, he transferred its guidance to his disciple Lavrentii and secluded himself in his cell.
During the time of a Tatar incursion against the Vologda region the Monk Kornilii, in protecting the brethren, set out with them to the Beloezersk outskirts. The monk died at age 82 on 19 May 1537. Many disciples of the Monk Kornilii were also glorified by sanctity of life: the Monks Gennadii of Liubimograd (Comm. 23 January), Kirill of Novoezersk (Comm. 4 February), Irodion of Iloezersk (Comm. 28 September), Adrian of Poshekhonsk (Comm. 5 March), Lavrentii and Kassian of Komel'sk (Comm. 16 May).
The all-church celebration to the Monk Kornilii (19 May) was established on 25 January 1600 by Patriarch Job and a council of bishops. The Life of the Monk was compiled by his disciple Nathanael in the year 1589. There exists a service and a praise to the Saint, and the Ustav written by the Monk Kornilii has been preserved.