Amazon is offering over 4,000 items through Amazon Pantry, including food, drink, household supplies, baby and child-care, pet, health, and beauty products. The goods are delivered within one day.
Amazon is said to have up to 50 million members overall and no less than 30 million to 40 million in the USA alone.
Retail experts had projected that the USA company was poised to launch its Amazon Fresh in the United Kingdom next year.
Amazon yesterday, challenged the UK's long-established supermarket with a countrywide pantry offer for members of Amazon Prime called Amazon Pantry.
Customers add as many goods as they like to a 20kg "pantry box" until it's full.
Amazon Pantry is also offered in the US, Japan and Germany.
The U.S. firm has been selling food and drink for four years through its Amazon Grocery Store.
The biggest difference with the European version is that Amazon guarantees next day delivery for a flat-rate £2.99, which translates into less than the $5.99 it charges for standard ground shipping in the U.S. Also, additional boxes in the United Kingdom cost just £0.99, which isn't an option here.
"If I had to isolate one (reason for faster growth), it's the adoption of Prime and utilization of Prime, driven by the incremental attributes of Prime", Wells Fargo analyst Matt Nemer told IBD last month.
"Amazon Pantry has been created to take the heavy lifting out of replenishing the often bulky basics and store cupboard essentials that people need every day", Amazon Pantry manager at Amazon United Kingdom, Helene Parthenay, said.
The move is the ecommerce giant's most ambitious foray into Britain's growing online grocery market but stops short of replicating its broader U.S. Amazon Fresh service, which offers about 20,000 chilled, frozen and perishable products and items from local shops.
Mintel, a London-based market research company, forecasts that online grocery sales in the United Kingdom will increase by 15 percent to £8.6 billion ($13.1 billion) in 2015.