Seneffe is a Walloon municipality located in the Belgian province of Hainaut. On January 1, 2006, Seneffe had a total population of 10,743. The total area is 62.77 km² which gives a population density of 171 inhabitants per km².
The municipality consists of the following sub-municipalities: Seneffe proper, Arquennes, Familleureux, Feluy, and Petit-Rœulx-lez-Nivelles.
The Château de Seneffe, now a museum belonging to the French Community of Belgium, is located in the municipality.
Seneffe was the site of a battle in 1674 between French and Dutch armies during the Franco-Dutch War.