Carnegie of Finavon represented Forfar from 1669 to 1674. He was made captain of a new company in the Scots Regiment of Guards on 25 August 1674 and served at the Battle of Bothwell Bridge before resigning his commission in 1680. He then served as commissioner for Forfarshire in 1686, from 1698 to 1702, and again from 1702 to 1707.