Thornhill is a suburban area in Cardiff, Cardiff
- Built-Up Area: Cardiff
- Parish/Community: Llanishen
- Unitary Authority: Cardiff
- Region: Wales
- Category: Populated Place
- Type: Suburban Area
- Latitude/Longitude: 51°32'29"N 3°11'33"W
- Eastings/Northings: 317378, 183198
- OS Grid: ST173831
- Mapcode Local: GBR HX.G3M6
- Mapcode Global: VH6F0.LJZ1
Location and coordinates are for the approximate centre of Thornhill within this administrative area.
Geographic features and populated places may cross administrative borders.