Following a degree in Business and Marketing, Steve King started his career in media sales, moving to the agency world in 1982 to join Bates Dorland. With the 1988 inception of Zenith Media in the UK (Bates Dorland was one of the contributing agencies), he was appointed director of TV Buying, overseeing the largest TV group of its kind in Europe.  He was made Deputy Managing Director in 1992 and Managing Director in 1993.

Steve moved to the US, initially to evaluate the feasibility of establishing Zenith Media in the USA.  When Zenith USA began operating in February 1995, he was made General Manager with principal responsibility for media operations, the management of key clients and the development of new business.  In 1996 he was promoted to Chief Operating Officer of the US business and became Chief Executive Officer, Zenith Media Europe, Middle East and Africa in August 1997.  Following the creation of ZenithOptimedia in October 2001, he was appointed Chief Executive of ZenithOptimedia EMEA and subsequently Worldwide CEO in March 2004.  The Zenith Optimedia Group is owned by Publicis Groupe SA and has almost 4000 employees across 170 offices in 60 countries.