The price cut follows a review by Northern Irelandʼs Utility Regulator.
The regulator imposes price controls on the major incumbent suppliers: electricity firm Power NI; SSE Gas in Belfast and the west; and Firmus in the Ten Towns network.
Prices at Power NI and SSE will remain at current levels.
The review of Power NI saw reductions to the wholesale energy element of their tariff, due to the fall in wholesale energy prices.
However, increased network expenditure due to net-zero reinforcements offset these potential savings.
Power NIʼs regulated tariff remains the cheapest regulated domestic electricity tariff in the UK and Ireland.
SSE recently reduced their tariff by 12.2%, effective from 1 July 2023, which reflected falling wholesale costs.
The review found that no further movement in the tariff was required.
John French, Utility Regulator chief executive, said a formal review of the costs in providing gas and electricity concluded that a 7.56% decrease is needed to Firmus Energyʼs Ten Towns domestic gas tariff.
"This means that the average domestic gas bill in Firmus Energyʼs Ten Towns licence area will decrease by approximately £112 per year," he said.
Mr French also said no changes were needed to SSEʼs regulated gas tariff or Power NIʼs domestic electricity tariff.
"We will continue to actively monitor wholesale energy and network costs and will ensure any falls in costs are passed through to customers at the earliest opportunity," he added.
40% drop this year
Firmus said its prices in the Ten Towns network will have dropped by 40% this year.
Prices in its Belfast network are not being cut in October but the company said they are being kept under review.
Industry data suggests that wholesale natural gas prices in the UK are now about 80% cheaper than they were this time last year.
However, last winter consumers were not fully exposed to abnormally high gas prices due to government support.
That support was phased out and ended in July.
Meanwhile data from the Northern Ireland Consumer Council suggests the price of home heating oil has risen sharply over the last two months as global wholesale prices increased.
Their data suggests that last week 500 litres cost on average about £370 compared to about £300 at the end of July.
However, that is still much cheaper than September last year, when 500 litres cost about £500.