The website is designed to be flexible to enable it to adapt to "emerging customer and technology trends" and will be backed by a "dedicated tablet experience" and an update of all its mobile sites and apps.
By moving away from the Amazon platform, M&S hopes to transform itself from a British retailer into an international, multichannel retailer, and a marketing campaign to promote the new site is planned for late spring.
A dedicated editorial hub called Style & Living, with content from fashion journalists, celebrities and guest editors, aims to strengthen M&S’s style credentials as the retailer seeks to turn around its clothing business.
M&S has a 50-strong software development team working on the site and has launched a software engineering-focused graduate scheme and a specialist digital lab to help create a start-up mentality to innovation and testing.
The retailer has been developing the website for years since poaching Laura Wade-Gery from Tesco at the beginning of 2011, to benefit from her expertise as head of Tesco.com and Tesco Direct.
The site has undergone more than two years of extensive testing with hundreds customers, and M&S claims this has enabled it to make functional updates including "a 14% improvement to the quality of search returns", to fulfilling a customer demand for more editorial fashion and lifestyle guidance.
Marks & Spencer launched its ecommerce site in 2007 in partnership with Amazon and hoped to launch a standalone ecommerce platform late last year.
Speaking about the Amazon partnership back in 2012, Wade-Gery said: "We've been renting the car rather than owning it. Amazon fundamentally sells everything as if it is a book and Amazon is pure-play only, meaning [the M&S ecommerce site] has tortured the system.
"Our scale and ambition is huge and we are putting real money behind this. M&S is putting more money behind this [than] I had at Tesco."