| Onhaye | |
| Picture-Legend: | Onhaye town hall |
| Map: | Onhaye Namur Belgium Map.svg |
| Map-Legend: | Location of Onhaye in Namur province |
| Arms: | Onhaye wapen.svg |
| Arrondissement: | Dinant |
| Nis: | 91103 |
| Mayor: | Christophe Bastin |
| Majority: | ICO |
| Postal-Codes: | 5520-5524 |
| Telephone-Area: | 082 |
| Web: | www.onhaye.be |
| Coordinates: | 50.25°N 54°W |
Onhaye (in French pronounced as /ɔ̃ɛ/) is a municipality of Wallonia located in the province of Namur, Belgium.
On 1 January 2006 Onhaye had a total population of 3,120. The total area is which gives a population density of .
The municipality consists of the following districts: Anthée, Falaën, Gerin, Onhaye, Serville, Sommière, and Weillen.
The region is home to several cultural heritage monuments, such as Château de Fontaine and the fortified farmhouse Falaën Castle.