Scottish Power has become the third major gas supplier to announce a price cut, with the news it is to reduce prices by 4.8% from 20 February.
Customers on the standard tariff will make an average saving of £33 on their annual gas bills as a result.
Earlier this week, the UK's largest supplier, British Gas, announced it was to cut prices by 5% from 27 February.
German-owned supplier E.On was the first to reduce its tariffs, by 3.5% - a cut that has already taken effect.
Scottish Power's reduction will affect 1.1 million of its two million customers, as the rest are on fixed-rate tariffs.
It follows a fall in wholesale gas prices of around 20% since the end of November.
Consumer groups have said the suppliers should therefore pass on much larger cuts than they already have.
"Just as with British Gas and E.On, Scottish Power's gas bill reduction has fallen short for consumers after rocketing prices," said Gillian Guy, the chief executive of Citizens Advice.
"Energy companies must look to pass on wholesale costs by cutting electricity bills, not just gas."
Scottish Power said it would continue to keep its prices under review.
However, it said its pricing reflected costs other than just the wholesale price of gas, which makes up about half a typical bill.
"Non-energy costs such as transmission and distribution networks and environmental and social obligations remain unaffected by any wholesale energy price movements," said Neil Clitheroe, Scottish Power's chief executive of retail and generation.