Kenneth Mackenzie, Lord Fortrose (c.1718–1761) was a British politician and (by right of his ancestry) Chief of the Highland Clan Mackenzie.
Mackenzie was the eldest son of William Mackenzie, 5th Earl of Seaforth (died 1740) by his wife Mary, only daughter and heiress of Nicholas Kennet of Coxhow, Northumberland. His father had taken part in the Jacobite Rising of 1715 and had forfeited his estates and title under the Act of Attainder of 1716.
Mackenzie supported the Government during the Jacobite Rising of 1745. He represented the constituencies of Inverness Burghs between 1741 and 1747, and Ross-shire between 1747 and 1761.
He died in London on 18 October 1761 and was buried in Westminster Abbey.
Mackenzie married (11 September 1741) Mary, eldest daughter of Alexander Stewart, 6th Earl of Galloway. She died on 10 April 1751. Their children were: