The move into e-commerce - marked by the launch of a revamped www.johnlewis.com Web site - follows the company's acquisition of the UK operational arm of US Internet retailer Buy.com in February.
The John Lewis Direct service, which will initially stock more than 5,000 lines focused on homeware and gifts, is based on Buy.com's technology and customer service platform.
Murray Hennessy, managing director of John Lewis Direct, said one of the main aims of moving into e-commerce was to extend the reach of the store.
"John Lewis is a strong brand name, but in terms of distribution there are only 26 outlets," he said. "Our research has shown that the average John Lewis customer is two to three times more likely to be online than the average UK consumer."
John Lewis has signed up digital fulfilment provider iForce to handle warehousing, picking, gift wrapping, packing, distribution and returns management. Customer management company ClientLogic will handle customer service by phone, e-mail and fax from its Exeter call centre.
Hennessy said the direct selling arm will soon be expanded to include catalogue ordering, as well as other categories of goods.
Although some high street retailers have pulled out of e-commerce, John Lewis is matched in its new move by rival department store Debenhams, which has revamped its e-commerce presence, adding the ability to monitor and personalise the way users navigate the site.
Using a customer relationship management application from software supplier Blue Martini, Debenhams can build user profiles, allowing the company to push relevant promotions, adapt online advertising and change the feel of the site according to individual shopping habits.
The site, www.debenhams.com, allows customers to check stock availability before proceeding to pay.
"On a Web site, you do not have much time to make an impression - if someone hits your site, you know they are looking to buy, so it is important that you do not give them any reason to leave," said Simon Hawkes, e-commerce director at Debenhams. "The site is part of our business rather than an add-on and we are able to generate loyalty to the whole brand rather than a single channel."