The publisher plans to update the sites of its biggest brands, including Good Housekeeping, Cosmopolitan and Country Living, within the next six months. The rest of the consumer websites will follow.
Each will remain free to access, offering more opportunities for user interaction - such as chat forums - alongside a mixture of magazine and web-only editorial and more archive material.
The head of ad sales for digital business will work with specialist ad agencies to generate commercial support, such as display advertising and sponsored web-only content.
Management of the sites will be integrated with that of the magazines and the editor of individual titles will oversee content on both platforms.
Duncan Edwards, NatMags chief executive, admitted that the publisher had been "sitting on its hands" regarding its digital strategy while it focused on acquisitions.
"Our sites currently offer a thin product that doesn't really add much value beyond driving subscriptions and merchandise sales," he said.
"Being a magazine reader is like being a member of a club and we want the sites to reflect that with compelling content, strong community tools and specialist services."
NatMags also wants to acquire external providers of web content and last week bought independent consumer health website NetDoctor.