The winery is located in the commune of Saint-Estèphe or the area of the same name in the Médoc (Bordeaux). It is separated from the famous Château Lafite-Rothschild only by a stream. A part of the vineyards was abandoned in 1789 and thus the Château Cos Labory was founded. Château Cos d'Estournel was founded in 1811, when the horse and wine merchant Louis-Gaspard d'Estournel (1753-1844) acquired the first vineyards. He had recognised the quality of the extremely poor gravel soils (Cos) at an early stage. The name "Cos" (Caux) is derived from "Colline de cailloux" (gravelly hill). Louis-Gaspard d'Estournel exported his wine to India and Arab countries. From there he imported noble horses, which were bred in the pastures around the vineyards. He built a huge wine cellar, partly in Asian style, including the pagoda-like curved roofs and the famous door from the harem of the Sultan of Zanzibar.
Estournel realised by chance the value of the wine's journey by ship in wooden barrels when unsold wine was brought back home from India. He compared it with the same wine that had stayed at home and found a considerable improvement in quality. At the time of sale, they achieved far better prices. Therefore, after some time, all wines were sent on a ship journey before being sold and these were marked with an "R" (Retour des Indes = back from India). One could therefore call him one of the "inventors" or at least the first user of barrique ageing (whether these barrels were already toasted is not known, however). In the medium term, however, this elaborate process led to a financial fiasco. Therefore, the estate was sold to the London banker Martyns in 1852. At the Bordeaux Classification in 1855, the château was then awarded second place (Deuxième Cru Classé) under the name "Cos Destournel".
After an eventful history, the estate came into the possession of Yves, Jean-Marie and Bruno Prats by inheritance in 1970. Bruno Prats acted as managing director until 1998. It was during this period that the term "Super-Seconds", which is so popular in the Médoc, was born. This means that the wine would earn the "Premier Cru Classé" because of its high quality. This was thanks to Bruno Prats, who worked with immense perfection and the most modern methods. In 1998 the estate was sold to the Taillan Group and finally in 2001 to the food manufacturer Michel Reybier. Today it is managed by Prats' son Jean-Guillaume.
The total estate covers 100 hectares, of which 67 hectares are planted with vines. These are Cabernet Sauvignon (60%), Merlot (38%) and Cabernet Franc (2%). The extremely long-lasting red wine matures for 18 to 24 months in 70% to (in particularly good years) 100% new . The second wine is called "Les Pagodes de Cos". The branded wine "Maître d'Estournel" produced under the appellation "Bordeaux" was created in 1971 by Bruno Prats. The name honours the legendary founder Louis Gaspard d'Estournel. The red wine is made from the Cabernet Sauvignon, Merlot and Cabernet Franc varieties, the white wine from Sauvignon Blanc, with grapes coming from the whole region. These are wines which are considerably cheaper in price.