Kate Moss for Topshop will launch next spring and the supermodel will be personally involved in creating the range, which the retailer believes could become a global brand.
Green said: 'She's going to work with our design team and will be very much involved, item by item.' Moss attracted controversy last year after lurid tabloid headlines, but the tycoon said: 'I feel comfortable. She passionately wants to do this and it's great.'
The deal was a highlight of one of the most high-profile London Fashion Weeks for UK retailers in recent years.
The British Fashion Council chief executive Hilary Riva said: 'Of course retailers take a big interest. They're investing in the creative future of the business.'
Topshop, Marks & Spencer and Superdrug are among the big-name retailers that sponsored London Fashion Week.
Riva said US retailers Barneys and Saks were also increasingly interested in London Fashion Week because 'UK designers are leading edge'.