Helen Dickinson, the new director general of the BRC, said the "stand-out" online performance came after slower momentum in the previous few months.
She said: "Many valued the ease and convenience of shopping online during the Christmas period. The surging popularity of tablets and smartphones giving even better access is a major factor."
She also said shoppers felt much more comfortable putting their credit card details into their mobile phones.
More top news
Speaking after the Westminster attack, Brad Smith exclusively told ITV News that Microsoft will only hand over data when legally compelled.
Kurt Cochran and his wife Melissa had been visiting London from the US to celebrate their 25th wedding anniversary and were due to fly home.
The Government has previously described the new coin - which enters circulation tomorrow - as "harder to counterfeit than ever before".