The position, director of comms and marketing, has been filled by Lesley Miles, who has been bookseller Waterstone's marketing director for the past six years.
Miles said her move had been prompted by a desire to experience a new sector, and that she has long admired the work done by the hospital.
GOSHCC raises funds for the London paediatric hospital, Great Ormond Street. The hospital has a fundraising target of £20m this year, and one of Miles's tasks is to devise a strategy that will help the charity double current fundraising revenues by mid-2009.
Much of the money will be used for the hospital's massive upgrade programme, which aims to redevelop two thirds of its facilities.
Miles will also bid to raise awareness of the charity, the hospital's international role and its training facilities - the biggest for paediatric care in the UK. She reports to GOSHCC executive chairman Charles Denton.
At Waterstone's, Miles was responsible for the popular high-street bookstore's brand marketing, advertising, promotions, national events and PR.
She was previously head of marketing at the RAC.