Russell Davies, who will take up the UK job in mid-February, will replace John Shaw, who will return to Portland to work on the Coca-Cola account after a two-year stint in London.
In 1999, Davies, a British native, moved to W&K Portland to work as the senior planner on Microsoft before becoming the planning director for the whole agency.
Davies said: 'I wanted to go back to what I have enjoyed most about advertising: making brilliant ads and working with a group of really good people I know very well, within the W&K ethos. Plus, I missed Match of the Day!'
Amy Lawson, the managing director of W&K London, said: 'Russell has a terrific sense of humour and a great understanding of contemporary culture. I am thrilled to have him.'