Scottish Power and EDF Energy have become the latest energy suppliers to announce significant price cuts.
Ofgem recently urged EDF's customers to switch supplier
Scottish Power said it will reduce domestic gas bills by up to 16.5% from 15 June, with electricity bills set to fall by as much as 5.5%.
EDF Energy, meanwhile, said it will trim its gas bills by more than 10%, and keep electricity prices the same.
Energy watchdog Ofgem had accused the firms of failing to pass on this year's decline in wholesale energy prices.
Last week, energy watchdog Ofgem publicly urged EDF customers to switch supplier in order to save money.
EDF said their pricing move, which comes into effect on 15 June, will cut the average bill of those customers who buy both gas and electricity by £63 a year.
Scottish Power said customers paying for both gas and electricity by direct debit would see their bills fall by an average of £75 a year.
All the "big six" UK energy suppliers have now vowed to cut prices since British Gas first reduced its bills in February.
EDF - which has 5.5 million UK customers - said it would not be reducing its electricity prices because its electricity bills saw the smallest price rises compared with competitors last year.
'Listening to customers'
The firm's chief executive, Vincent de Rivaz, described its cut in gas prices as a "sensible move".
"We listen very carefully to what our customers are telling us," he said.
"Over recent years our customers have benefited from our careful management which has protected them from the highest prices."
However, some analysts questioned whether EDF was right not to also cut electricity prices, wondering whether it will lose customers as a result.
British Gas announced a further price cut last week, reducing its electricity bills by an additional 6% and gas by 3%, with immediate effect.
The UK's other main electricity and gas suppliers are Npower, Powergen, and Scottish & Southern Energy.