Wellin (; ) is a municipality of Wallonia located in the province of Luxembourg, Belgium.
On 1 January 2007 the municipality, which covers , had 2,958 inhabitants, giving a population density of 43.8 inhabitants per km<sup>2</sup>.
The municipality consists of the following districts: Chanly, Halma, Lomprez, Sohier, and Wellin. Other population centers include: Barzin, Froidlieu, Fays-Famenne, and Neupont.