The third son of John Campbell, 5th Duke of Argyll, John Douglas succeeded his brother, George William (6th Duke), as 7th Duke of Argyll in 1839. He married firstly on 3 August 1802 to Elizabeth, eldest daughter of William Campbell of Fairfield. She died without children in 1818. In 1820 he married Joan Glassel [d. 1828]; they had two sons and a daughter. The Duke married a third time in 1831 to Anne Colquhoun Cuninghame [d. 1874], widow of Dr. George Cunningham Monteath. His eldest son having died at the age of sixteen, the Duke was succeeded by his second son, George Douglas, as 8th Duke of Argyll.