In her new role, she will lead the agency's international American Express business from the London office, running the account across 30 markets outside of the US.
King replaces Paul Jackson, the former Ogilvy chief executive, who has left the agency without a job to go to. Jackson is believed to be in negotiations with WPP about an alternative role.
Ogilvy has been without a UK chief executive since Jackson was moved to head Amex last year. Gary Leih, the Ogilvy Group UK chairman, is handling the chief executive's responsibilities as part of his role.
The move sees King return to London after three years working in the US.
She left JWT London in 2004 to become the global business director on the Kraft advertising account at JWT New York and was named the president of JWT Chicago in 2005. In that role, she worked with Graham Woodhall, the executive creative director at JWT Chicago, and reported to the regional president of JWT Worldwide, Rob Quish. She also retained control of Kraft across 50 markets.
Ogilvy declined to comment as Campaign went to press.