Shields will report to Michael Birch, co-founder and chief executive, and will be responsible for expanding Bebo's international business.
B is a challenger to the News Corporation owned , and now has more than 8m users in the UK who spend an average of 145 minutes a day on the site.
Birch said: "Joanna has a stellar track record in the online media and entertainment world and a proven ability to transform high-potential companies into high-growth businesses. She is an accomplished leader with an extensive network in the UK, Europe and beyond -- this makes her the natural choice to take responsibility over all international matters at Bebo."
Shields said: "There is a true revolution of personal expression under way. Social networks provide a unique platform for people to connect with others anywhere in the world in new and innovative ways. Bebo is at the forefront of this phenomenon and has tremendous potential to connect its massive user base with media companies, brands and artists worldwide."If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .