Born Caroline Mary Macleod, in or about 1784, the eldest daughter of Lieutenant-General Sir John and Lady Emily Macleod, in 1816 she married Sir Robert William Gardiner (1781-1864), veteran of the Peninsular War and Waterloo; KCB, 1814. From 1848 to 1855 her husband was Governor of Gibraltar. According to his obituary in the Times (29 June 1864), he was survived by two children, Colonel Lynedoch Gardiner, and Emily, married to Major George Freud.

Lady Caroline Mary Gardiner appears on the 1871 census, living with her son, Colonel Henry Gardiner and his family, at 31, Bryanston Square, Marylebone, London. She died in Marylebone, London, in 1876, at the age of 92.