Magnus, which has been developed by Hearst Magazines Digital Media, integrates the publisher's content management, syndication, community tools, subscription marketing, universal user registration and promotional tools.
NatMag said that the move would enable it to share "development and best practices".
So far Youandyourwedding.co.uk, Company.co.uk, Menshealth.co.uk and Handbag.com have been migrated to Magnus, while Harpersbazaar.co.uk, Babyexpert.com, Cosmopolitan.co.uk, Esquire.co.uk and Allaboutyou.com will make the transition by the first quarter of 2011.
NatMag said Magnus will make it easier for readers to move across websites, eliminating the need for re-registering their personal details. It will also improve search capabilities and offer advertisers a "technically sophisticated environment in which to engage with their target audiences".
Simon Horne, NatMag's general manager and finance director, said: "Our investment in the Magnus platform will create many opportunities for NatMag's websites – from the creation of new revenue streams to providing users with a more efficient and faster service, which, in turn, will help generate significant growth in traffic and attract new advertisers."
John Loughlin, Hearst Magazines' executive vice-president and general manager, said: "The Magnus platform, which we built in-house at Hearst, has proven to be a highly effective system for managing our rich digital content both on our sites and with syndication partners, and has enabled us to offer registered consumers a seamless experience across our network."