Standing charges for both fuels is also to fall by a similar percentage.
Bord Gáis Energy has become the latest energy supplier to cut its prices.
The company is to reduce its unit rates for both electricity and gas charges by 15.5%.
Standing charges for both fuels is also to fall by a similar percentage.
The provider says the reductions will lead to a reduction of €274 in the average gas bill and €357 in the average electricity bill.
The cuts will take effect from November 9.
Bord Gáis Energy has more than 600,000 customers across the country.