Clare County Council has confirmed it is to purchase Holy Island in Lough Derg.
The local authority believes the historic site could attract an estimated 20,000 tourists a year.
The island is regarded as one of the most important monastic sites in the country, with strong connections also to Brian Boru.
His brother Marcan was abbot there in 1008, while the monks burial ground, known as The Saints Graveyard, is unique in Europe in that it has remained undisturbed for 1,000 years.
The council aims to improve visitor access to the 43 acre island, while also protecting the islands sanctity and tranquillity.
The plan to open access to the island is supported by Waterways Ireland, who say it could form part of a heritage trail along Ireland's inland waterways.
