The supplier says that it intends to enter both markets simultaneously - and hopes to concentrate on the industrial and commercial market as a first priority and then expand into domestic markets afterwards.
"Our intention is to become a significant new player in the Irish market," the company's energy supply director Alistair Phillips-Davies said.
"We will initially aim to sell a range of electricity and gas products which may then be followed by renewable products, metering, telecoms and energy services."
Mr Phillips said that the deregulation of the Irish market represented a real opportunity for the UK energy supplier.
Click here to run an energy price comparison, and see if you could be paying less for your gas and electricity.