A total of 900,000 people switched energy supplier in March alone, figures from energy regulator Ofgem have shown.
Consumers have had to pay more for their gas and electricity
The figure was 200,000 up on the normal monthly figure and reflected a series of price rises across the gas and electricity industry, Ofgem said.
Over the past two years energy prices have risen by more than 40%, driven by rising wholesale energy costs.
Ofgem added that customers who had never switched supplier could save £110 a year on average by doing so now.
"Recent price rises have seen large numbers of customers vote with their feet and take advantage of the competitive market to change their energy supplier," said Alistair Buchanan, Ofgem chief executive.
"The latest figures show that the number of people switching is the highest it has been for four years," he added.
In response, the Energy Retailers Association told BBC News that they welcomed the uplift in switching as it highlighted the "competitive" nature of the UK energy market.
March was a bad month for energy customers.
According to consumer group Energywatch, five of the UK's six biggest energy suppliers raised their prices during the course of the month.
This, it seems, prompted customers to shop around for a cheaper deal.
However, with prices rising across the board, Energywatch told BBC News that switching supplier was no "panacea".
Instead, a longer term solution, securing the UK's energy supply was needed, the group added.
"We need the (government's) energy review to address some of the deep-seated issues over which consumers have no control," said Adam Scorer, director of campaigns at Energywatch.