The renovation of the Grade II listed building will aim to epitomise "Mayfair elegance" and attract the luxury market when the work is complete.
London-based RPW Design has been charged with the project, which includes the refurbishment of all 152 bedrooms, the lobby, executive lounge and meeting rooms. Five new suites will also be added.
Luxury materials such as leather, silk, solid wood and bookmatched marble will be used throughout the hotel, which will feature quintessentially British touches such as British artwork, Edward Goodyear hand-picked wild flowers and Floris bathroom amenities.
The guest experience will also be enhanced with the introduction of a signature arrival and bespoke personal service, Apple products throughout, Bluetooth LCD screen TVs and mobile check-in.
Nicolas Kipper, the newly appointed general manager, said: "We aim to compete with the best hotels in London with an exclusive and unique Marriott offering. The new design, an increased suite count, an elevated service and an enhanced in-room offering, will make us even more appealing to the luxury market."
RPW Design’s managing director Jan Wilson added: "Our designs aim to bring out the English Heritage of the Francis Verity designed historic building extending its intimate feel and residential character into the hotel’s interior. Elegantly designed rooms and public spaces will have all the facilities expected in a leading luxury hotel."