Houstoun is a surname. Notable people with the surname include:
John Houstoun (1744 – 1796), American lawyer and statesman from Savannah, Georgia
Dr. William Houstoun (botanist) (1695–1733), British surgeon and botanist
William Houstoun (lawyer) (1755–1813), American lawyer, Continental Congressman for Georgia
Sir William Houstoun (fl. 1830s), British army officer, Governor of Gibraltar