The invasion of Poland was the 1939 joint invasion of Poland by Nazi Germany, the Soviet Union, the Free City of Danzig, and a small Slovak contingent, that marked the beginning of World War II.

Invasion of Poland may also refer to:

• World War II
  • German invasion of Poland, 1939
  • Slovak invasion of Poland, 1939
  • Soviet invasion of Poland, 1939
• Soviet invasion of Poland (1920)
• Polish–Russian War of 1792
• Second Swedish invasion of Poland, 1702–1706
• Battle of Hodów, 1694 invasion of Poland by the Crimean Khanate
• Battle of Khotyn (1673), 1673 invasion of Poland by Ottoman Turks
• Swedish invasion of Poland, 1655–1660
• Battle of Khotyn (1621), 1621 invasion of Poland by Ottoman Turks
• 1589 invasion of Poland by the Crimean Khanate
• Third Mongol invasion of Poland
• Second Mongol invasion of Poland
• First Mongol invasion of Poland