The appointment of Willingham, who during a six-year stint at TBWA\London ran the Sony PlayStation account, is seen as an attempt by Fallon to strengthen its hold on the £70 million pan-European Sony business.
In April this year, David Patton, the former PlayStation client, was promoted to the role of senior vice-president of communications for Sony Europe, with a remit that included overseeing Fallon London's Sony output.
Willingham had developed close working ties with Patton while at TBWA.
In June last year, he was hired to work at Grey by its then chief executive Garry Lace, leading to speculation Grey had set its sights on capturing Sony.
Mark Finnock, a planner, who worked primarily on five at TBWA, is also moving to Fallon. However, it is unclear if he will be working on Sony.
Fallon picked up the pan-European Sony ad business in November 2002, following a pitch against Bartle Bogle Hegarty, Wieden & Kennedy, Abbott Mead Vickers BBDO, Rapley Smith & Jones and the incumbent agency, Saatchi & Saatchi.
Willingham and Fallon both declined to comment on the story.