The son of Sir Archibald Macdonald (d. 1826) and Lady Louisa Leveson-Gower; educated at Westminster School, he was MP for Tain burghs (1805-06), Newcastle-under Lyme (1806-12), Sutherland (1812-16), Calne (1816-31), and Hampshire (1831-32); he was clerk of the Privy Seal.