She will take over the day-to-day running of i-D magazine from founders Terry and Tricia Jones, following Vice Media Group's purchase of i-D in December last year.
The husband-and-wife duo is stepping back from daily operations, but remain partners and shareholder in the business. They said: "Fiona Dallanegra returning to i-D as the new publisher is a classic i-D success story. We're delighted to welcome her back."
Dallanegra was fashion editor of the bi-monthly style bible from 1997 to 2001.
She was subsequently employed by Chanel as a director for its makeup studio in Paris, before returning to the UK in 2011 for a variety of consulting projects for luxury firm Moët Hennessy Louis Vuitton SA.
Vice, which owns the ad-funded free lifestyle magazine Vice and vice.com, plans to use i-D's following to expand into the fashion market, and will launch an online fashion channel in September.
The new channel will be video-focused, using original content to explore fashion from high-end couture, to underground scenes from around the world, as well as leading personalities in fashion and culture.
The Vice Media group is backed by WPP and includes record label Vice Records, full-service creative agency Virtue Worldwide and book-publishing division Vice Books.