St. Kevin was the son of Coemlog and Coemell, who were of Leinster nobility. He was baptized by Saint Cronan of Roscrea, and educated by Saint Petroc of Cornwall from age seven. He lived with monks from age 12 and studied for the priesthood in Cell na Manach (Killnamanagh). He ws ordained a Priest by bishop Lugidus. He became a Monk and was an acquaintance of Saint Comgall, Saint Columba, Saint Cannich, and Saint Kieran of Clonmacnois.

Following his ordination, he lived as a hermit for seven years into a cave at Glendalough, a Bronze Age tomb now known as Saint Kevin's Bed, to which he was reportedly led by an angel. He wore skins, ate the nettles and herbs that came to hand, and spent his time in prayer. Word of his holiness spread, and he attracted followers, including Saint Moling. Founded the monastery at Glendalough, which included relics brought back during a pilgrimage to Rome. This house, in turn, founded several others, and around it grew a town which became a see city, though now subsumed into the archdiocese of Dublin. Served as abbot for several years. When he saw that the monastery was well-established, he withdrew to live as a hermit. Four years later, however, he returned to Glendalough at the entreaty of his monk, and served as abbot until his death at age 120. King Colman of Ui Faelain entrusted Kevin with raising his son.

Noted as a man who did not always like the company of men - but was at home with the animals, as some of the legends surrounding him show:

• During a drought, Kevin fed his monks with salmon brought to him by an otter. When one of the monks considered making gloves out of the otter's pelt, it left and never returned.
• Once during Lent, while he held his arms outstretched in prayer, a blackbird laid an egg in the Kevin's hand. He remained in that position until the baby bird hatched.
• A cow which habitually licked Kevin's clothes while the saint was in prayer gave as much milk as 50 other cows.
• Lacking milk to feed the son of King Colman, Kevin prayed for help. A doe arrived to provide for the baby. When the doe was later killed by a wolf, Kevin chastised the killer; the wolf then provided the milk herself.
• A young man with severe epilepsy received a vision that he would be cured by eating an apple. There were, however, no apple trees about. Kevin, seeing the lad's need, ordered a willow to produce apples; twenty yellow apples appeared on the tree.
• In his old age, King O'Tool of Glendalough made a pet of a goose. As time passed, the goose also became aged and weak, and finally unable to fly. Hearing of Kevin's sanctity and power, the pagan king sent for him, and asked that he make the beloved goose young. Kevin asked for a payment of whatever land the goose would fly over. As the goose could no longer take flight, O'Toole agreed. When Kevin touched the bird, it grew young, and flew over the entire valley that was used to found the monastery of Glendalough.
• A boar was being chased by a group of hunters with their dogs. It ran to where Kevin sat praying under a tree, and cowered beside him for protection. When the dogs saw the saint in prayer, they laid on their stomachs, and would not approach the boar. When the hunters decided they would ignore the man and kill the boar, a flock of birds settled in the tree above the praying saint. The hunters took this as a sign, and left man and beast alone.