The supermarket has revealed plans to open its first dedicated Online Fulfilment Centre over the "next few years" in Bromley-By-Bow, East London, to sustain its growing online grocery sales.
Sainsbury’s estimates the 185,000 sq ft facility, laid out in the same way as its supermarkets and staffed by 375 employees, will serve an additional 20,000 customers a week.
The brand currently delivers to more than 190,000 online customers per week.
Jon Rudoe, Sainsbury’s director of online, digital and cross-channel, said: "We work hard to ensure we deliver the very best service to our customers and the opening of the new centre will enable us to maintain this.
"The site will be purpose built with the Sainsbury’s customer in mind and will support our existing store based operation, something that will continue to be the foundation of our online grocery business."
Tesco has already opened six "dark stores" in the London area, and is believed to be exploring possible sites in Birmingham and Manchester
Separately, it has been reported that Morrisons is considering launching its own eagerly-awaited e-commerce operation in January with a trial in Birmingham.
Earlier this year, the supermarket struck a 25-year deal with internet grocer Ocado to make its first foray into online grocery,