Energy supplier E.ON will increase prices by an average of 3.7% from January 18.
Energy firm E.ON said it does not expect to have to raise prices in the next 18 months "as a result of social or environment obligations".
E.ON said in a statement that the Government's energy announcement "should mean our customers pay less next year".
"There remains a risk, however, that increases in network charges or wholesale energy costs for example could force a price increase", it said in a statement, adding, "But the company very much hopes that situation does not occur".
Tens of thousands of pensioners will face a hike in energy prices after E.ON withdrew its discount tariff for over-60s.
The StayWarm deal, which offered fixed-price energy for older customers based on their average consumption levels, will come to an end from 7 October.
The energy firm says the move has been forced by changes to the number of tariffs permitted by regulator Ofgem.
A spokesman said: "We are writing to all customers as their contracts come to an end, and where possible we are also contacting them by phone with the aim of speaking to each customer to help ensure they switch to the best product for their needs."
Customers with one of the "Big Six" suppliers will soon be able to compare their energy use with that of their neighbours in a bid to reduce their household bills.
E.ON has teamed up with US company Opower, which works with utilities to save consumers money, to launch an online 'saving energy toolkit' to help them understand their energy use.
Consumers will see their electricity and/or gas use compared with 100 anonymous E.ON customers with homes of a similar size and type, and against the most energy efficient homes in their local area.
The scheme gives households a breakdown of where and when energy is used in the home, including a "what uses most" chart that splits current usage into heating, lighting, hot water, appliances and other use.
It will also detail how energy use changes from month to month, and compare costs for the current month to the previous month, showing how bills have been affected by weather and usage.
German energy giant E.ON's 9.4% winter price rise for British customers generated an extra £381 million in revenues for the company after the UK endured the worst spring temperatures in decades.
Financial results showed E.ON's revenues rose 9% to £4.47 billion during the first half of 2013, compared to the same period last year, following on from big gains made by rival energy firms.
The Dusseldorf-based company said British gas consumption over the period increased by 10% due to the freeze.
E.On's announcement today is the latest in price hikes from energy firms:
- British Gas imposed an average increase of 6% affecting 8.5 million customers from November 16.
- Npower's average rise of 8.8% for gas and 9.1% for electricity came into force on November 26.
- EDF Energy's 10.8% price rise for domestic gas and electricity came into force last week.
- SSE, which trades as Southern Electric, Swalec and Scottish Hydro, increased its tariffs by 9% on October 15.
- Scottish Power hiked bills by an average 7% on December 3.
- E.On has approximately 4.8 million domestic customers.
- 800,000 of the energy firm's customers are on fixed tariffs and will not be hit by the price hike.
- From January 18, a typical standard dual fuel customer, who pays by cash or cheque, will see their bill rise by around £110 a year to £1,370.
We have held back from increasing our prices for as long as we possibly could and at the same time have worked hard to reduce our own costs as a business so that our customers can get the best price possible. However, some 16 months after our last price increase, and almost a year since we actually cut our electricity prices, we have had to make the difficult decision to increase our prices.
In the next few days every customer affected by this price change will receive a letter from us explaining the detail behind this announcement. Wherever we can, we will include the likely impact on the customer's own bill.
Energy firm E.On will increase electricity prices by 7.7% and gas prices by 9.4% from January 18, the company has said.
The average dual fuel price will increase by 8.7%.
All of the major energy companies have now announced a price rise for UK customers.
Energy firm E.ON is to announce an 8.7 percent rise in dual fuel prices on Monday, according to The Sun newspaper.
Electricity prices will increase by 7.7 percent and gas by 9.4 percent, the report says.
The news today comes as rival provider EDF's 10.8 percent price hike takes effect.