The SRA, which asks restaurants to answer 70 questions relating to sourcing, environment and society before determining a score, gave River Cottage HQ at Park Farm 87 per cent and The River Cottage Canteen in Axminster 84 per cent.
As a result, both restaurants become Three Star Sustainability Champions - the SRA's top rating.
To be a Sustainability Champion a restaurant must be able to prove it is sustainable on a daily basis, by serving local, seasonal, high welfare food in a restaurant where the resources and waste are managed efficiently, the staff are well treated, the customers respected and the community valued.
George Clark, account manager at the SRA, said the Three Star rating reflected River Cottage’s 'formidable commitment to sustainability across the board'.
He said: “River Cottage doesn’t just talk about sustainability, it practices it too and its very high score reflects this.
"We were particularly impressed with their steadfast commitment to sourcing produce locally and also their dedication to reduce the environmental impact of both sites. It will be tough for another restaurant to top this score, but it sets a great target for others to aim at."
River Cottage's Axminster site scored 100 per cent in its food waste category - most leftover food is composted and leftover cooking oil is converted into biofuel for the local community college.
Other examples of the company's commitment to sustainability include using a rocket composter to feed fruit and vegetables at River Cottage HQ, installing a biomass boiler and building a relationship with local schools. The restaurants were also commended for their sourcing of ingredients from a wide variety of local suppliers: fish is sourced daily directly from fishing boats for example.
River Cottage managing director Rob Love said: “Sustainability is core to River Cottage and we continue to strive to achieve the highest standard. We support the work the SRA is doing, encouraging other businesses to become more sustainable and giving them the tools and knowledge to do that.”
River Cottage Restaurants will join Petrichor at the Cavendish Hotel in London and The Royal Oak in Bishopstone as Three Star restaurants.
The SRA’s Star Rating system, which scores restaurants and pubs across 14 areas of sustainability, has become the industry standard and will be included in a number of restaurant guides from later this year. Already The Times restaurant critic Giles Coren includes an SRA rating as part of his reviews.
More than 300 restaurants are on track to be star rated by the end of the year and the SRA is currently working with more than 600 of them across the UK.