Online grocery sales in UK supermarkets doubled to 12.5% in December, up from 6.7% in the same period last year, the latest data from Nielsen has revealed.
In the four weeks to 24 December, around 8.5 million households, or just over 30% of all households, shopped for their Christmas groceries online.
It reflects an increase from 5.7 million households over the Christmas period in 2019, the study noted.
UK head of retailer and business insight at Nielsen, Mike Watkins, said, "2020 marks the first Christmas where online shopping played a significant role in consumers' shopping behaviour, with 85% of the incremental sales in food and drink made online in the last four weeks ending 26 December.
"Although overall grocery growth was a little lower than in November, this takes into account the many challenges consumers faced around restrictions and cancelled Christmas plans."
Store visits declined by 10%, with shoppers increasing their spend per visit to an average of £20 from £17 last year.
This figure is slightly lower than the all-time high of £22 witnessed during the peak of the lockdown in May 2020.
Data also showed that customers spent almost £12 billion at UK supermarkets in the four weeks ended 26 December, with online sales accounting for £1.3 billion of the total.
Total sales in tills increased by 8.4% in this period, resulting in the biggest increase on record for supermarkets in December.
Shoppers held back some spending in the final two weeks leading up to 24 December following COVID-19 restrictions and smaller family gatherings.
Beer, wine and spirits emerged as the fastest-growing category, with traditional indulgences remaining popular with consumers.
Sales of champagne grew by 18%, while crémant sparkling wine saw a 51% growth.
Data also revealed a significant increase in demand for tequila (+59%), flavoured vodka (+50%) and spiced rum (+47%) as consumers experimented with cocktail making in the festive period.
Watkins explained, "It has certainly been an unusual Christmas for us all, and this has affected purchasing decisions. The pandemic has changed how we live, shop and consume and despite consumers celebrating the festivities in smaller groups, food and drink remained at the heart of celebrations. With fewer people to entertain and cater to, many households took the opportunity to enjoy less traditional meals."