UK online retail sales saw a 16.4 per cent increase in December 2012 compared to the previous year, according to IBM Cloud research.
Boxing Day had the strongest percentage increase with sales up 45 per cent on last year. IBM said online shoppers spent an average of £100 per transaction during the Christmas season, overall.
IBM's Digital Analytics Benchmark, a Cloud-based analytics platform that tracks e-commerce transactions, analysing raw data from 150 retailers it the UK, also found that mobile shopping traffic made up a quarter (24.2 per cent) of all online sessions on retailers' sites.
Mobile shopping hit a record high of 33.6 per cent on Christmas Day itself.
IBM's findings also show a strong November, where online retail sales were up 13.7 per cent over the same period in 2011. iPad-based traffic in November tripled year-on-year, according to the data, growing more than 200 per cent.
"This provides another clear reminder to retailers of the need to optimise browsing experiences for mobile devices," said Chris Withers, UK head of smarter commerce at IBM.
In earlier research it was estimated that UK retailers could have lost £147 million of revenue during Christmas due to missed sales opportunities through out-of-stock products, and an additional £1.7 billion to their competitors as consumers moved to other websites for their Christmas gifts.
The research, which was commissioned by NetSuite, and based on economic models provided by the Centre for Economics and Business Research (CEBR), found that across 100 UK retail IT managers and 2000 UK consumers, the average retailer was losing 10 per cent of their Christmas revenue through out-of-stock situations. Ageing IT systems were partly blamed.