Applegreen has secured approval from the Competition and Consumer Protection Commission to buy a 50% share in the Joint Fuels Terminal in Dublin port from the Topaz Energy Group.
The deal is worth about €15.7m.
The transaction was first announced in January and is expected to be complete by the middle of this month.
The Joint Fuels Terminal is one of three fuel importing facilities in the port.
The stake being acquired was previously owned by Esso Ireland.
When it first announced the deal in January, Applegreen said it was expected to boost earnings from this year.
Applegreen said the proposed deal provides it with the facility to import fuel directly from refineries, "thereby securing a strategically valuable platform that provides a competitive supply for the majority of its Irish fuel requirements".