Electric Ireland is to increase its residential electricity and gas prices by 4% from April 1.
The company said the increases are as a result of sustained increases in wholesale energy prices.
The price hikes announced today equate to €3.20 extra a month (including VAT) for Electric Ireland's electricity customers.
For the company's gas customers, the rise equates to €2.49 a month (including VAT).
Electric Ireland has over 1.1 million electricity customers and almost 140,000 gas customers, according to latest figures from the Commission for Regulation of Utilities.
Daragh Cassidy, from price comparison and consumer website bonkers.ie, said Electric Ireland last November promised to freeze its prices over the winter months when many of its competitors had already increased theirs.
He said there was an inevitability about today's announcement.
"Electric Ireland is now the second energy supplier to announce a price hike in 2019 after Bord Gáis Energy announced an increase earlier this month.
"But as Ireland's largest electricity supplier in terms of customer numbers, this increase will be felt far and wide by consumers," Mr Cassidy said.