Key was one of several high-profile publishers to leave Emap following its recent restructure, which resulted in 175 redundancies across the group. She was most recently director of teen magazines Sneak and Bliss.
Emap subsequently exited the teenage magazine market by closing Sneak, as well as selling Bliss to Panini.
In more than a decade at Emap, Key held a number of positions, including publisher of More!, publisher of Emap Australia's parenting titles and commercial director of its UK online music portfolio.
Bebe left her position as managing director of Emap Elan at the end of 2006 to launch the new website, which is backed by venture capitalist firm Brightstation Ventures.
The site, which targets women aged 25 to 40, is one of several fashion-oriented websites launching this year. These include Hachette Filipacchi's elleuk.com, Conde Nast's stylefinder.com and IPC's instylemagazine.co.uk, which went live last week.
Contrary to reports, it is understood that osoyou.com is not the project that Bebe was working on while she was still at Emap.