The company is the fourth of the big six energy suppliers to introduce a price rise, following SSE, British Gas and npower.
Around 2.3 million Scottish Power households are expected to be affected by the price rise, which will see the average annual bill increase by more than £100.
The price rise was blamed on a 34 per cent increase in the cost of delivering government energy efficiency schemes, an 11 per cent rise in transport and distribution costs, and an 8 per cent increase in wholesale energy prices.
Neil Clitheroe, ScottishPower’s CEO of retail and generation, said: “We will be writing to all those affected customers over the coming weeks explaining what the price increase will mean for them.
“We will also give advice on how they could reduce the impact of these increased costs. We understand that this is a difficult time for many people and we encourage our customers to contact us.”