Davies, who is also the chairman of W&K's account planning group, has worked at the agency for the past seven years, four of which were spent at W&K's head office in Portland in the US.
In London, Davies has worked on various Nike campaigns including "freestyle" and "run London". He was also instrumental in winning the Honda account in 2001.
In his new role, Davies will be based in London for the first year and may return to the US to Nike's Portland headquarters after that.
Stuart Smith, a planner at the agency for the past two years, will take up the reins of the planning department. Smith has worked on Nike, Aiwa and Honda, for which he won a gold IPA Effectiveness Award last year.
Previously, he spent six years at D'Arcy, where he worked on clients including COI Communications, Tetley and Procter & Gamble. Latterly, he was promoted to the board. He has also worked at Young & Rubicam as an account planner.
Neil Christie, W&K's managing director, said: "Stuart has made a massive contribution to the success of this agency and to the business of our clients. This is a richly deserved promotion."
Smith added: "These are exciting times at Wieden & Kennedy as it is."