The news comes despite the fact the firm actually lost 70,000 customers.
The huge increase in profits took the energy suppliers total earnings up to Â£390m in 2012 - Â£77m up on the Â£313m it made in 2011.
Despite losing 70,000 customers last year, the firm said the 3.9m other customers it serves had used more energy due to the cold weather.
The firm was one of five of the 'Big Six' energy providers to bump up its prices last year, hitting its customers with a nine per cent energy bill price hike in November 2012.
npower chief executive, Paul Massara, said: "We have invested billions in the UK, and although, at less than five per cent, our profit margin remains significantly lower than other FTSE businesses, we are now beginning to see the benefits of that investment as our mix of different power station technologies provides a reliable, efficient energy supply."
The firm is the latest supplier to announce high profits this year; just over a week ago British Gas reported a profit increase of 11% with the firm generating a revenue of over Â£606m for the year. Last month EDF also confirmed a 7.5% rise in profits.
To help customers combat increased energy bills, the Government launched its Green Deal scheme at the end of January. Many energy suppliers, including npower, are participating in the scheme, offering subsidies on items such as solar panels or the fitting of a more energy efficient boiler in order for customers to save energy on their household bills.
Latest gas and electricity news brought to you by UK Power - the energy price comparison site.
Click here to run an energy price comparison, and see if you could be paying less for your gas and electricity.