Flogas has signed an agreement to acquire Just Energy's business in Ireland, subject to approval from the Commission for Regulation of Utilities.
The companies said there will be no impact on supply to the 10,000 Just Energy Ireland residential and commercial customers during the transfer period.
Once the deal is approved, customers will receive communications from Flogas about their accounts.
The news follows the decision of Just Energy to exit the Irish market following an evaluation of its operations here.
John Rooney, managing director of Flogas, said the company is working to ensure a smooth transfer of operations.
"Our priority is to ensure that our new customers continue to receive a great standard of service," Mr Rooney said.
"To support this, we are investing heavily in new IT, CRM and ERP systems, and actively recruiting to boost resources in sales, marketing, energy trading and risk management," he added.
On transfer to Flogas, some individual tariff details may change but Flogas has assured customers that their annual estimated bill should not increase.
Flogas has been operating in the retail energy market since 1978 and already supplies natural gas and electricity to over 35,000 residential and commercial customers in Ireland.