Wieynk replaces Tim Pierce, AKQA's chief operating officer, who has acted in the role since January 2007 when Michael de Kare-Silver, the former European managing director, left the agency.
In his new role, Wieynk will be responsible for AKQA's London and Amsterdam offices. He will focus particularly on building the Amsterdam office, which the agency is hoping will become a gateway for expansion into Europe.
Nick Constantinou has also been appointed to the newly created role of UK general manager to oversee technology and delivery. He moves from New York, where he was the director of delivery. Jason Whiting, the managing director of the Washington office, will now also take responsibility for the New York office.
Tom Bedecarre, the AKQA global chief executive, said: "It has been apparent for years Guy should eventually be in this role. He's always brought great insights to our clients' business as well as the agency."