The 5.3% rise will add around £64 to a typical dual fuel annual bill and will come into effect on 17th June.
It is made up of an average increase of 4.4% on gas and 6.2% on electricity, which means householders will pay £1,230 yearly.
The Big Six supplier said the price rise “largely stems from increases in policy and wholesale energy costs”.
It has launched a new Price Freeze June 2022 tariff exclusively for those customers who will be affected, costing £1,166 on average.
Simon Stacey, Managing Director for Domestic Markets at npower said: “Announcing this price change today isn’t a decision we’ve taken lightly. The costs all large and medium suppliers are facing – particularly wholesale and policy costs which are largely outside our control – have unfortunately been on the rise for some time and we need to reflect these in our prices.”