Brendan the Navigator founds a monastery in about 542 on Eilach, presumed to be the island, possibly because of the combination of its isolation and good grazing.

This may make the remains the oldest extant church buildings in Britain, although the earliest written record of its existence dates from the late ninth century.

Columba is believed to have visited the island and it is one of the proposed locations of the Columban retreat isle of Hinba.

Eileach an Naoimh may be the burial site of Columba's mother Eithne.