Onhaye () 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.