Clarke moves from Ket-chum Newscan in Hong Kong where he was senior vice-president and head of the corporate practice from December 2000 to January 2002.
Previously he worked at Arthur Andersen in Hong Kong, as regional head of marketing and comms.
Clarke also formerly worked at Hill & Knowlton in Hong Kong and Toronto.
At BT, he co-ordinates external comms across the Asia-Pacific region, including Australia and Japan.
Former deputy vice-president at Ketchum, Denise Kaufmann, replaced Clarke as vice-president.
Last month, BT's network services and solutions business, BT Wholesale, hired Burson-Marsteller in the UK (PRWeek, 18 October).