The Treaty of Washington may refer to:

  • Treaty of Washington (1805), between the U.S. and the Creek National Council (Muscogee (Creek))
  • Treaty of Washington (1824), two Indian nation treaties, between the U.S. and the Sac (Sauk) and Meskwaki (Fox) (7 Stat. 229), and the Iowa (7 Stat. 231)
  • Treaty of Washington (1826), between the U.S. and the Creek National Council led by Opothleyahola
  • Treaty of Washington (1828), between the U.S. and the Cherokee, Arkansas Territory
  • Treaty of Washington, with Menominee (1831), between the U.S. and the Menominee Indian tribe
  • Treaty of Washington (1836), a U.S.–Native American (Ottawa and Chippewa) treaty
  • Webster–Ashburton Treaty of 1842. It settled the border dispute between Canada and the Eastern States, such as Maine and Vermont. It helped to end the slave trade
  • The Oregon Treaty of 1846, which established the US–British frontier west of the Rocky Mountains (today's US–Canada boundary)
  • Treaty of Washington (1855), between the U.S. and Ojibwa
  • The Treaty of Washington (1871), a general agreement between the United States and the British Empire
  • The International Meridian Conference of 1884 in Washington DC, establishing the Greenwich Meridian, the world time zone system and the universal day as international standards
  • The Treaty of Washington (1900) between Spain and the United States
  • The Washington Naval Treaty of 1922 that limited naval armaments
  • The North Atlantic Treaty of 1949 that created NATO
  • The Treaty of Washington (1989), Treaty on Intellectual Property in respect of integrated circuits
  • The Convention on International Trade in Endangered Species of Wild Fauna and Flora, better known as CITES