Shoppers spent about £78 on average.
Online retail sales jumped 18% to £8.1bn during January 2014, as average basket values rose to £78 during the month, according to the lastest IMRG Capgemini e-Retail Sales Index.
IMRG CIO Tina Spooner said: "While growth in the online clothing sector slowed to just 9% year-on-year, the average spend for this sector was up 6% on the same month last year, which may be an indication that retailers were discounting less following a strong performance over the festive trading period.
"The number of browsers converting to buyers reached the highest levels recorded in the month of January since 2009 and this, together with the 18% annual growth in e-retail sales, appears to be evidence that we are seeing an overall increase in consumer confidence.
"As we would expect, sales of travel peaked during January, however, the surge of 233% from December is the highest month-on-month performance ever recorded for this sector."
During the first month of the year, British shoppers spent about £78 online on average, exclusive of travel, which is up from £76 in December and £74 during the corresponding period last year.
Sectors reporting growth during the period include home and garden (21%); and health and beauty (23%) year-on-year, while travel sector reported a growth of 233% from December.
Capgemini Retail Consulting and Technology VP, Head Chris Webster said: "As we settle in to a new year, with the shopping bonanza that was Christmas behind us, it is very reassuring to see such impressive results and is a clear indication that consumer confidence is being sustained.
"This will of course be welcomed by retailers and puts us in a very good position for a strong 2014."