Esso Ireland is also being acquired as part of the deal
Topaz Energy Group is to be acquired by global retailer Couche-Tard.
The company will join the publicly-quoted Canadian business, which has a worldwide network of 15,000 convenience stores and service stations.
The two companies signed an agreement that will see the acquisition of Topaz Energy Group Ltd - together with linked companies Resource Property Investment Fund plc and the recently-acquired Esso Ireland Ltd.
The transaction is expected to close in Spring 2016, subject to regulatory approvals.
Couche-Tard already has operations in North America, Europe (Norway, Sweden, Denmark, Poland, the Baltics and Russia), Asia and the Middle East.
Some 100,000 people are employed in its network across the world.
Topaz is Ireland's largest convenience store and fuel retail business with 464 service stations - 162 of which are company-owned - and a commercial fuels operation with over 30 depots.
The business employs more than 2,000 people across the island of Ireland.
Welcoming the announcement, Topaz chairman John Callaghan said; "The last two years have been a period of phenomenal development and improvement for the company".
"With the steadfast support of the board, our management and staff, we have established a well capitalised group of growing businesses which, with the recent amalgamation of Esso in Ireland, is the undoubted industry leader".
While Topaz CEO Emmet O'Neill described the transaction as a "game changer" for the retail sector in Ireland.
"Couche-Tard is one of the strongest names in retail in the world and their presence in Ireland will transform the retail sector here", he added.
Newstalk.com's business editor Vincent Wall told Lunchtime the deal could be worth €500m.