Fermanagh was a kingdom of Gaelic Ireland, associated geographically with present-day County Fermanagh.
Fermanagh may also refer to:
- County Fermanagh, one of the six counties of Northern Ireland
- County Fermanagh (Parliament of Ireland constituency) until 1800
- Fermanagh (UK Parliament constituency) 1801–85
- Fermanagh GAA, intercounty sport team
- Fermanagh District Council, one of the 26 district councils of Northern Ireland, covering a slightly larger area than the county
- Fermanagh Township, Juniata County, Pennsylvania, USA
- Viscount Fermanagh junior title of Earl Verney
- Baron Fermanagh junior title of Earl Erne