The agency will devise a new brand positioning for the organisation, as part of a plan to double its fundraising revenues by mid-2009.
The move follows the appointment of MediaCom to the charity's £1.5m media planning and buying account in May.
The pitch was overseen by Lesley Miles, the charity's communications and marketing director. She joined from Waterstone's, where she was marketing director, in August last year to take up the new top communications and marketing role, and is responsible for raising awareness of the charity, as well as increasing its fundraising revenues.
The charity already uses WWAV Rapp Collins, which is responsible for the majority of the charity's direct response TV advertising and direct marketing activity.
Great Ormond Street Hospital is regarded as the world's most famous children's hospital, and houses the broadest range of paediatric specialists in one hospital.
The hospital treats around 150,000 patient visits each year, and only those with complex, life-threatening or life-limiting conditions.
It is currently battling with overcrowded conditions and hopes to raise extra funds to redevelop the hospital to allow patients, staff and families more space.
Miles was unavailable for comment at the time of writing. DraftFCB declined to comment.