Energy provider PrepayPower is to increase its electricity prices by nearly 10% from next month.
The company is also to increase its gas prices by almost 20%.
The business has 170,000 electricity customers and 60,000 gas customers.
It said the increase is in response to continuing increases in energy prices on both the national and international markets.
The changes take effect from July 1.
As a result of the increases, customers will on average pay around €3.05 more a week for electricity and €4.65 for gas.
"These increases are a result of rising energy costs internationally," a spokesperson said.
"Our hedging strategy has enabled us to avoid some of the larger increases that others have had to pass through but clearly any increase is regrettable."
Over recent weeks a number of companies have announced tariff increases as a result of the soaring cost of wholesale energy.
Electric Ireland raised its residential electricity prices by 23.4% and gas prices by 24.8% on May 1.
Bord Gáis Energy also increased what it charges for electricity by 27% and for gas by 39% on April 15.
While SSE Airtricity also put up its tariffs on May 1.
Yesterday, Spanish energy supplier Iberdrola announced it is exiting the Irish gas and electricity retail market following an internal strategic review that found market conditions and pricing were a barrier to its planned growth and ambitions.
In January, another new electricity provider, Bright Energy, announced that it was exiting the Irish market following a strategic review.
Taoiseach Micheál Martin warned Irish consumers yesterday of a "new era" of high energy prices because of Russia's war on Ukraine.