Mr Sze will support Robert Chiu, executive chairman, and Albert Chiu, chief executive, the Zurich-listed firm said in a statement.
Most recently, Mr Sze was Asia head for high net worth clients at Citi Global Wealth Management, and prior to this he was Asia head of investment and products.
From 2001-2007 he was CEO of Barclays Private Bank in the Asia Pacific Region, and before that worked for Morgan Stanley Private Clients and American Express Bank (where he was head of Private Banking). Mr Sze began his career at Citibank Private Bank in 1986.
EFG International’s business in Asia was founded in 2000. Initially based in Hong Kong and Singapore, it is now also present in Bangkok, Jakarta, Manila, Seoul and Taipei. The business has about 400 employees, including more than 160 client relationship managers.