| Viaur | |
| Pushpin Map: | France#France Occitanie |
| Mouth Coordinates: | 44.1442°N 1.9669°W |
| Subdivision Type1: | Country |
| Length: | 168km (104miles) |
| Source1 Elevation: | 1070m (3,510feet) |
| Discharge1 Avg: | 6m3/s |
| Basin Size: | 1530km2 |
The Viaur (in French pronounced as /vjɔʁ/) is a 168adj=midNaNadj=mid river in south-western France. It is a left tributary of the Aveyron. Its source is in the southern Massif Central, north of Millau. It flows generally west through the following departments and towns:
The Viaur flows into the Aveyron in Laguépie.
Its main tributary is the Céor.