The nation's largest energy supplier is freezing its standard tariffs for the winter.
It follows action by SSE, which became the first major supplier to promise a price freeze, saying it was capping standard household energy tariffs until April 2017. Renewable power firm Good Energy became the first supplier to guarantee it will not raise gas and electricity prices this winter last month.
The move by British Gas will put pressure on its rivals to follow suit and comes amid building political pressure on the big names to treat their loyal customers more fairly.
In a statement Mark Hodges, chief executive of British Gas, said: "We will be keeping the price of our standard variable energy tariff unchanged through this winter. It's already one of the cheapest standard deals available, and this move will help bring some peace of mind to more than six million of our customers."
It has also launched a deal which British Gas says will allow households to fix their energy prices for three successive winters through to March 2019. It said it will ensure customers can access its best deals.
But MoneySavingExpert's founder was not impressed with the announcement. Martin Lewis said: "Let me be plain, nobody should be given peace of mind by that."
"The reason British Gas and SSE feel the need to promise a price freeze is because the huge increase in wholesale prices and the weakness of the pound means we’re seeing massive inflation in the energy market," he added. "So this is almost certainly just a delay of price rises. Come the end of winter, expect to see hikes of up to 10 per cent by many of the Big Six companies."
Last month, business secretary Greg Clark met industry representatives following claims that energy suppliers were profiteering from loyal customers.
Clark said a report from Energy UK which the Sun obtained a copy of, "appears to confirm my concern that the big energy firms are punishing their customers' loyalty rather than respecting it".
He added: "Customers who are loyal to their energy supplier should be treated well, not taken for a ride, and it's high time the big companies recognised this."
A recent report from uSwitch found a third of working families were already struggling to foot their energy bills, despite there being no "major" price hikes for almost three years.
Britain's Big Six energy providers