The chef and his wife Eléna, who have run the Dorset restaurant for 12 years, will hold their last service on 25 April before handing over the keys to a new owner.
Brown said he was pleased to have agreed a sale for the business and was looking forward to working on his consultancy business, which he set up four years ago.
"We have had an amazing run at Sienna and are both immensely proud of our achievements during the last 12 years, so there is a degree of sadness in closing but I relish the new challenges ahead and I am looking forward to building Creative about Cuisine into a significant business within the hospitality sector," he said. "I am incredibly passionate about this industry and food in general so the opportunity to continue working within the sector, albeit in a different vein, is hugely exciting.”
Creative about Cuisine will offer a consultancy service for restaurants, hotels, cafes and food producers as well as one-to-one chef coaching, menu and recipe development. Brown also plans to work with Kingston Maurward College and be involved in guest chef dinners around the country.
In the last month of business, Sienna will donate £5 from every booking to industry charity Hospitality Action. Eléna said: “This is an exceptionally worthwhile charity to support; it is the industry’s main benevolent organisation and covers a number of roles including crisis grants and employee support programmes. We hope to raise over £500 in our last month.”