EDF Energy is cutting tariffs by up to 12.5% for electricity customers.
The reduction will affect 2.3 million of its customers, with an average change of 8.8% from March 31.
The move follows recent price cuts from E.ON, British Gas and Scottish and Southern Energy.
EDF Energy said the price cut applied to standard rate electricity customers in London, the South East, South West, Wales and Scotland.
The reduction follows lower wholesale energy prices, but the company warned that the market is volatile and the outlook for retail prices remained "challenging".
Eva Eisenschimmel, head of brand performance at EDF Energy, said: "Today's announcement confirms our ongoing commitment to providing our customers with more competitive prices during these difficult economic times."
The move also ensures that EDF Energy is in line with Ofgem recommendations calling for regional electricity pricing differentials to be addressed, the company said.
E.ON announced on Thursday that it would cut average electricity prices by 9% from March 31, following the decision last week by Scottish and Southern Energy to cut average electricity prices by 9% and gas prices by 4% from March 30.
British Gas earlier revealed that it would cut the price of its standard tariff by 10% for 75% of its customers from February 19, saving them an estimated £79 a year on the average household gas bill.
EDF Energy, which has taken over the Government's stake in British Energy, supplies gas and electricity to more than 5.5 million customers.
