Gas supplier Firmus Energy is cutting prices for its customers outside Belfast by more than 20% from April.
That will mean a typical annual household bill will fall by £135.
The Firmus 'Ten Towns' network supplies about 50,000 customers. The firm also has a network in Belfast that will be subject to separate price announcement.
The main reason for the price cut is a significant decrease in wholesale gas costs.
"This saving follows on from a previous reduction of 8.77% in October last year and means that natural gas is now almost 30% cheaper than last summer," said Michael Scott, managing director of Firmus Energy.
The utility regulator said the move could herald a wider cut in energy prices.
Its chief executive, Jenny Pyper, said: "In relation to electricity, we have begun a review with Power NI regarding their domestic regulated tariffs and expect an announcement in the coming months.
"Whilst we can't pre-empt the outcome, given the falls being seen in wholesale prices, I would be hopeful of a positive outcome for electricity consumers before the summer."