Siege of Louisbourg may refer to:
- Siege of Louisbourg (1745), the capture of the settlement by British forces during the War of the Austrian Succession
- Siege of Louisbourg (1758), the capture of the settlement by British forces during the Seven Years' War, after which it was permanently ceded to the British
See also
- Louisbourg Expedition
- Louisbourg Expedition (1757), a cancelled British plan to capture Louisbourg during the Seven Years' War
- Duc d'Anville Expedition (1746), a failed French attempt to capture Louisbourg