He will oversee the agency's two largest accounts, SingTel and Hewlett Packard.
King ends a three-year stint on the client side, latterly as product manager for L’Oréal's Lancôme and Kiehl’s brands. He has also had spells at TBWAShanghai and Saatchi & Saatchi London.
King said: "I have long admired the work of BBDO from the client benches. With so much momentum at BBDO Singapore, I leaped at the opportunity to join the planning team."
Andy Wilson, BBDO Singapore's head of planning, and chairman of BBDO Asia's planning council, added: "I am delighted Jason has joined our planning team. He is a bright prospect, and will bring terrific experience and enthusiasm to the position."