The Union Flag is the name of the flag of the United Kingdom.

Union flag may also refer to:

• Flag of the African Union
• Flag of Europe, also called the Flag of the European Union
• Flag of the Kalmar Union
• Flag of the Soviet Union
• Flag of the Union of South Africa
• Grand Union Flag, the first national flag of the United States
• Flag of the United States (also called "Union")
  • Union flag, of the Union during the American Civil War
• Union mark of Norway and Sweden
• The Union Flag, newspaper published in Tennessee