John Graham (1774 – 6 August 1820) was an American politician and diplomat. He was born in Dumfries, Virginia and graduated from Columbia University in 1790. He moved to Kentucky and served in the Kentucky legislature.
From 1801 to 1803 he served as secretary and chargé d'affaires in the U.S. legation to Spain. From 1804 to 1807 he was secretary of the Orleans Territory.
Graham was chief clerk of the State Department from 1807 to 1817 and as such was acting United States Secretary of State for five days in March 1817, at the start of the administration of President James Monroe. Along with Caesar Augustus Rodney and Theodorick Bland, Graham was selected by Monroe in 1817 as one of three commissioners for a special diplomatic mission to South America, the South American Commission of 1817-1818. He served as the U.S. Minister to Portugal at Rio de Janeiro from June 1819 to June 1820.
He died in Washington, D.C. on August 6, 1820. His brother, George Graham, was acting Secretary of War under Presidents Madison and Monroe.