He took monastic vows at the Kiev Gniletsky Assumption Monastery, where he spent his days in incessant work and deep heartfelt prayer. Out of obedience to the brethren, he accepted the rank of hieromonk.
Upon reaching spiritual maturity, St. Gerasim went to the north of Russia and came to the Vologda River. Here he built himself a hut and, in the silence of solitude, gave himself up to divine thought, incessant prayer and psalmody. 
Gradually becoming closer to the locals, the monk wished for their spiritual salvation to build a temple in the name of the Holy Trinity and establish a monastery at it. Thanks to the patience and tireless efforts of the saint, the Trinity Kaisarovsky Monastery, the first and oldest in the northern borders of Russia, is being created.
During his life, St. Gerasim enlightened the Vologda region with the light of the gospel teaching: he converted some from paganism to Orthodoxy, strengthened others in faith and supported them in observing the commandments of Christ. The monk died on March 4, 1178, and after his death his relics became a source of grace-filled gifts and healings. Moreover, the saint himself appeared to the sick, who did not know him at all, and ordered them to go to his tomb, promising at the same time healing from various ailments.