Eir, the Republic's largest telecoms provider, has sold its tower infrastructure company to Phoenix Tower International for €300m (£268m).
Under the terms of the deal, Eir has sold the entire share capital of Emerald Tower, its mobile telecom infrastructure management business.
Proceeds from the sale will be used to accelerate the roll-out of Eir's 4G and 5G networks. In addition, it provides the company will more money to invest in its mobile network.
Eir will retain ownership of the base stations, antennae and all telecom-related equipment, including fibre.
Eir and Phoenix will be entering into a long-term agreement for the provision of hosting services over the infrastructure, as well as the construction of new sites through a build-to-suit programme, according to a statement from Eir.
Carolan Lennon, chief executive of Eir, said: "This transaction allows us to accelerate the roll-out of our expanded 4G and 5G networks and increases Eir's capacity to further invest in our mobile network.
"It will help us deliver the best mobile experience for all our customers across Ireland, enabling more efficient infrastructure roll-out in the future to further increase geographic coverage."
The transaction is expected to close this summer.
Last year Vodafone Group spun off its European mobile mast infrastructure.
Following the latest deal, Phoenix Tower will have over 9,000 towers, 986km of fibre and more than 80,000 other wireless infrastructure and related sites throughout Ireland, the US and other countries such as Argentina, Bolivia and Colombia.