He effectively replaces John Shaw, the former joint worldwide planning director of Ogilvy & Mather, who announced last month that he was leaving the agency to become the strategy and planning partner at Rapier.
Davies, who starts his new role in September, spent nine years at Wieden & Kennedy, eventually becoming the planning director in 2002.
During his time there, he worked on various Nike campaigns including "freestyle" and "Run London", and played an integral role in winning the Honda ad account.
He left W&K in February 2005 to join Nike as its global planning director, but left a year later to launch his own consultancy, the Open Intelligence Agency.
Since then, he has worked as a consultant for companies including Apple, as well as writing regular columns for Campaign and Wired.
A prolific blogger, he has also written a book, based on the blog of the same name, called Egg, Bacon, Chips And Beans: 50 Great Cafes And The Stuff That Makes Them Great, which provides a guide to the best cafes in the UK.
Daniel Sicouri, the chairman of Ogilvy & Mather, Europe, the Middle East and Africa, said: "I know that Russell will be a magnet for talent and an inspirational leader."