Currently British shoppers spend one in 13 pounds online, but this will change to one in five pounds by 2020, says the report, to which retail research specialist Verdict contributed.
Ebay is attempting to cast 2020 as the tipping point when independent high street retailers need to have developed a presence on the internet to survive.
While online currently accounts for a quarter of all new retail businesses, this will rise to more than half over the next ten years.
Annual online spend is predicted to grow by £46bn or 223%, and offline spend to drop by £18bn or 7%.
The biggest growth will come in categories such as clothes and footwear, predicted to be up 351%, and health and beauty, up 330%.
Neil Saunders, from Verdict, said: "Traditional bricks and mortar shops simply cannot afford to ignore the potential growth opportunities available online."
The report includes a statistic from a survey of 508 business sellers operating on eBay - 79% of those with bricks and mortar businesses claim they couldn't have kept their high street presence alive without being online at the same time.
This article was first published on brandrepublic.com