Elliot served as Governor of Bermuda from 1846 to 1854. He supported the implementation of the mark system by penal reformer Alexander Maconochie in the Bermuda hulks. He later served as Governor of Trinidad from 1854 to 1856 and Governor of Saint Helena from 1863 to 1870. In St. Helena, Elliot supported botanist Joseph Hooker's plan to culture the Cinchona plant on mountainous parts of the island. A gardener was sent from the Royal Botanic Gardens, Kew, and Cinchona plantations soon sprang up near Diana's Peak.