The Jardine, later Buchanan-Jardine Baronetcy, of Castle Milk in the County of Dumfries, is a title in the Baronetage of the United Kingdom. It was created on 20 July 1885 for the businessman and Liberal politician Robert Jardine. He was head of Jardine, Matheson and Co, merchants in China, and also represented Ashburton, Dumfries and Dumfriesshire in Parliament. Jardine married Margaret, daughter of John Buchanan Hamilton and sister and heiress of John Hamilton-Buchanan, Chief of Clan Buchanan. The second and third Baronets were also heads of Jardine, Matheson and Co. The latter assumed the additional surname of Buchanan.

Jardine, later Buchanan-Jardine baronets, of Castlemilk (1885)

The heir apparent is the present holder's only son, Jamie Rupert Buchanan-Jardine (born 1994)