EDF Energy will cut its gas bills by 5% from 7 February, after a fall in the cost of wholesale gas prices.
It is the first of the major suppliers to announce a cut and it's likely the others will follow.
EDF has lowered its prices after mild weather over the winter months sent the price of wholesale gas falling.
In November, the company increased its gas bills by 15.4%, following rising wholesale gas prices.
Smaller supplier Ovo Energy has already cut its prices by 5% and Co-op Energy by 3%.
Today's announcement has sparked rumours of a price-cutting war among the Big Six energy providers.
"The recent price reductions by two small suppliers and the plunge in wholesale energy prices mean residential price cuts of 5 to 10% could be just around the corner. This would mean the average annual dual fuel bill falling by as much as £135," says Mark Todd, director of energyhelpline.com.
"A reduction of any sort would be welcomed by millions of customers who have been fighting a losing battle against shrinking disposable incomes and a seemingly relentless rise in the cost of living," he adds.