SPIRIT at the St Mary's Hall Hotel has become the first eating place in the islands to win a top rating from the Sustainable Restaurant Association.
The organisation said owner Clifford Freeman's dedication to welfare-friendly meat from animals reared on his own farm and his policy of sourcing locally produced seafood, eggs, fruit and vegetables earned him the three-star accolade.
Spirit scored highly for its healthy eating, supply chain and provenance policies and its efforts to treat people fairly, and was praised for using free-range eggs.
An environmentally friendly approach to recycling, cleaning products and energy consumption was also commended.
"It's clear from its sustainability rating that Spirit takes its environmental and social responsibility very seriously," said Mark Lineham, managing director of the SRA.
St Mary's Hall Hotel, a former townhouse built just before the Second World War by Italian nobleman Count Louis Adolphus Léon Ferrari, was in administration when Mr Freeman, a farmer from Gloucestershire, acquired it back in 2009. He thanked chef Phil Fallows and his team for their part in gaining the award, saying: "We're very proud to have achieved a three-star award from the SRA at our first attempt and full credit must go to the fantastic team who make St Mary's Hall and Spirit Restaurant such a wonderfully welcoming place."