Saint-Denis (French pronunciation: [sɛ̃ dəni] ⓘ; Walloon: Sint-Dnis) is a sub-municipality of the city of Mons located in the province of Hainaut, Wallonia, Belgium.

It was a separate municipality until 1964.

In 1964, it was merged into Obourg.

On 1 January 1972, Obourg was merged into Mons.

[1] This Hainaut Province location article is a stub.