The retailer is to offer more than 150 lines from this autumn's collection through Tesco Direct, with extra emphasis on the women's range, followed by children's wear.
The move will heap pressure on rivals such as Asda, Sainsbury's and Morrison to offer more non-food products over their websites.
Asda, Sainsbury's and Waitrose all offer consumers online retail services. This month the Waitrose-backed Ocado website launched a multimillion-pound ad campaign through CHI & Partners, to back its online shopping service.
However, many of Tesco's rivals focus on grocery shopping, whereas Tesco Direct sells household items and electrical goods.
Tesco already generates £1.2bn of turnover from its internet operation, Tesco Direct, and boasts 500,000 registered customers at ClothingatTesco.com, which allows users to browse the supermarket chain's clothing lines, but not buy it online.
An announcement is expected this week when Tesco reports its interim results, with analysts expecting the group to report the slowest growth in its core UK market in more than seven years.
Sales, excluding fuel at its UK stores, are expected to rise by an average of 3%, several points lower than the same time in 2006.
The figures are expected to be hit by bad weather and tough comparables in 2006. However, the supermarket giant will highlight online sales as a star performer.
At the same time, Tesco is expected to announce that Laura Wade-Gery, chief executive of Tesco.com, will become chief executive of Tesco Direct as well, replacing Steve Robinson, who left earlier this month.