Marriott's London head quarters and its 20 London-based hotels have been awarded the Green Globe certification.
The chain is the first in the capital to have reached the required standards of environmental sustainability demanded by the scheme.
Marriott received the certificate on the basis of its Echo (environmentally conscious hotel operations) programme, which aims to reduce energy consumption and carbon emissions.
Echo focuses on water and energy conservation, respecting and preserving wildlife, clean air initiatives, waste management and clean-up campaigns in the local community.
Stuart Bowery, general manager of the Marriott County Hall Hotel and chair of Marriott's London Business Council, said: "We are delighted to be among the first UK hotels to have achieved Green Globe certification. It is testament to our commitment to reducing the environmental impact of our business activities, and recognises the efforts of every one of our associates at every level in the company."
Green Globe, which was set up by the World Travel and Tourism Council (WTTC) in 1994, is the only global environment/sustainable development certification programme for the travel & tourism industry.
By Kerstin Kühn