He was educated at a private school at Wimborne and at Eton and then at Oriel College, Oxford, where he obtained a degree in 1827, and finished his education with a tour of the Continent.
He went into politics. His campaign for the Portsmouth parliamentary seat failed in 1838, but he was elected for Wilton in 1841.
Malmesbury was a Conservative protectionist, and he helped organize the protectionist cause in the House of Lords after the collapse of Sir Robert Peel’s Conservative government, which was occasioned by the act repealing the Corn Laws in 1846.
He served as foreign secretary in the government of the fourteenth Earl of Derby from February to December 1852. In this role, he quickly accepted the peaceful intention of Napoleon Ill’s second empire in France and attempted to maintain good relations with France. He was soon out of office with the failure of the Derby ministry but returned with the formation of another Derby government in February 1858. He held the office of foreign secretary again until June 1859, and during this period was mainly concerned with ensuring peace among France, Austria, and the Italian states, as the latter were increasingly asserting their rights of political independence. He attempted at first to get both Austria and France to evacuate the Roman states and to modify their controls over all of the Italian states; but he adopted a policy of strict neutrality after war broke out in May 1859, still offering his services in the cause of peace.
For the rest of his life Malmesbury remained a prominent Conservative politician in the House of Lords. He was Lord Privy Seal between 1866 and 1868, became leader of the House of Lords in 1868, and was once again Lord Privy Seal between 1874 and 1876. He died on 17 May 1889.
He married Lady Emma Bennet, the only daughter of the fifth Earl of Tankerville, on 13 April 1830.