Internationalist may refer to:

• Internationalism (politics), a movement to increase cooperation across national borders
• Liberal internationalism, a doctrine in international relations
• Internationalist/Defencist Schism, socialists opposed to World War I
• A member of the:
  • First International, or International Workingmen's Association, (1864–1876), an organization aimed at uniting various left-wing groups
  • Second International, (1889–1916), the original Socialist International
  • International Brigades, volunteers from different countries, who fought for the Second Spanish Republic in the Spanish Civil War (1936–1939)
  • League for the Fourth International, a Trotskyist international organisation whose most noteworthy section is the Internationalist Group in the United States
• Internationalist Review, an e-journal founded in Maastricht
• The Internationalist, a magazine based in Seattle
• Internationalist (album), a 1998 album by Australian band Powderfinger
• New Internationalist, an international magazine that works for social justice