The proportion of households who do all their grocery shopping online has doubled since 2014 according to new figures.
Research from analysts Mintel shows those who chose to shun the supermarket aisles has risen from 7% to 14%.
The figures also showed that 48% of consumers do at least some grocery shopping online, up from 43%.
Mintel said the market would grow by 12% this year after an increase of 15% in 2016 – compared to growth of just 1.5% for the overall food retail sales.
It forecast that online grocery sales would reach £11.1bn in 2017, up from £9.9bn in 2016.
Nick Carroll, senior retail analyst at Mintel, said: “Online grocery is the quickest growing grocery channel.”
He said younger consumers were far more likely to shop online, while the rise of smartphones and improved internet connectivity has “created an expectation from consumers that they can get what they want, whenever they want it”.
The research also pointed to a potential threat to the main supermarkets from discounters such as Aldi and Lidl.
Three in five of those who shop online said they would be happy to purchase a full weekly shop from a discounter.
Mr Carroll said the impact of the cut-price shops – which have been grabbing market share from the likes of Tesco, Sainsbury’s, Asda and Morrisons – had so far been “limited to physical retail to date”.
“Our research shows there will certainly be a market for the discounters if they decide to take the plunge into online retailing,” he added.