| Orneau | |
| Name Other: | Ôrnô |
| Subdivision Type1: | Country |
| Subdivision Name1: | Belgium |
| Source1 Location: | près de Meux |
| Mouth Location: | Jemeppe-sur-Sambre |
| Mouth Coordinates: | 50.4494°N 4.6791°W |
| Progression: | Sambre |
| River System: | Meuse |
The Orneau (pronounced as /fr/; Walloon: Ôrnô) is a river in Belgium. It is a tributary of the Sambre and therefore sub-tributary of the Meuse.
The Orneau flows from north to south, through the province of Namur, and after a journey of about 25km (16miles), it flows into the Sambre at Jemeppe-sur-Sambre.