According to Barclaycard, the amount spent by people shopping online is increasing by 11 per cent on average per year as access to smartphones and tablets continues to rise.
A survey commissioned by Google also found more than 30 per cent of Britons have made a purchase on a smartphone, the highest of any European nation, with 68 per cent of UK residents now using a such a device.
The Barclaycard research shows music downloads have become the fastest-growing sector for online spending, with sales up more than 120 per cent on last year. More than 75 per cent of all music purchases now take place online.
Chris Wood, Barclaycard's managing director, said: "Online shopping has come a long way since it first emerged in 1984 and now accounts for one in every £5 spent on credit and debit cards in the UK.
"More and more of us are turning to the web to research, compare prices and buy everything from cinema trips and electronics to the latest fashions."
IMRG, the UK's online retail association, says the rise of mobile devices is driving the rise in online spending, with the firm's research showing 45 per cent of visits to online retailers come from smartphones and tablets.
Andrew McClelland, chief operations and policy officer at IMRG, said: "Today's consumers are just getting to grips with the opportunities."