Power joined Burger King four years ago taking on the marketing director role in 2008.
During her time at the fast-food outlet, she was responsible for the launch of both a value and premium food offering, and the introduction of its brand character “The King” to the UK last year.
It is not known if she has a job to go to.
The chain has reported sliding sales and profit in recent months in the ever competitive fast food market.
Burger King was bought by New York-based private equity group 3G Capital in September last year.
Power is the latest high profile marketer to leave the chain. In May, Burger King’s most senior European marketer David Kisilevsky left the fast food chain to join ad agency McCann Erickson. Global chief marketing officer Russ Klein also left at the end of 2009 and was replaced by Coca Cola marketer Natalia Franco in May 2010.
The chain has recently launched an iPhone app and standalone dessert bar, designed to broaden the appeal of the brand outside of its fast food restaurants.