Working with editor-in-chief John Bryant, Roussel will develop the content strategy for Telegraph.co.uk, as well as news products on other digital channels including mobile phones, podcasts and Blackberries.
During 11 years at Bloomberg, Roussel held posts including global managing editor and bureau chief in London, Paris and Brussels.
He left the financial news service in 2004 and has since been working as a consultant for financial PR firm Holloway & Associates.
Murdoch MacLennan, Telegraph Group chief executive, said: "Edward has a wealth of news and commercial experience, as well as energy and insight. He is the right person to drive forward the Telegraph's distinctive and highly important online development."
The commercial side of the Telegraph's digital operations is headed by Annelies van den Belt, who joined from Times Newspapers last May.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .