The revamp, to be unveiled later this month, will include a greater emphasis on in-depth analysis of news stories. The current site replicates the printed Daily Mirror.
Mirror Group's online relaunch follows recent changes to the newspaper after heavy investment in new press facilities by its parent company, Trinity Mirror.
Richard Webb, the managing director of Mirror Group, said: "Digital is a crucially important part of our future. The way to success is to offer something complementary to the newspapers. We've delivered a site that has much improved navigability and usability, but now we will be introducing a much more radical content model."
The site's content will be produced by the Mirror editorial team, led by the editor, Richard Wallace, and implemented by the website editor, Steve Anglesey.
- Headliner, page 13.