Designed by interactive marketing and technology agency, Agency.com, the new site aims to make it easier for users to access financial services.
It features online application forms and self-service tools that allow customers to manage savings and credit card accounts online.
Sainsbury's reported a 600 per cent increase in purchases of products, such as life cover, instant-access savings accounts and personal loans, online.
Derek Bottom, deputy chief executive at Sainsbury's Bank, said: "The new site is an important part of our ongoing strategy to offer fresh banking and it is vital if we are to capitalise on the growth of online and supermarket banking. NOP research shows that 2.3 million people bought retail financial products online last year," he added.
Andy Hobsbawm, managing director for Agency.com:Europe, said: "We are thrilled to be helping Sainsbury's to achieve its goals by delivering the best possible online experience."