The Commission for Energy Regulation has announced that electricity bills for the ESB's residential customers will be cut by 5.4% from 1 November this year.
Reductions in ESB bills for small and medium business customers have also been announced.
ESB's 1.9m residential customers will see their bills reduced by an average €50 a year from November.
Bills for small business customers' bills will fall by 5.9% and medium businesses will see 10% reductions.
According to the Commission for Energy Regulation, the reductions reflect the lower market prices that the ESB pays for the gas it uses to power its stations.
It is the first reduction in ESB prices in 20 years.
Last week the CER said household gas prices would fall by almost 10.6% from October.
