| Chaumont-Gistoux | |
| Map: | Chaumont-Gistoux Brabant-Wallon Belgium Map.svg |
| Map-Legend: | The municipality of Chaumont-Gistoux in Walloon Brabant |
| Arms: | Blason ville BE Chaumont-Gistoux.svg |
| Flag: | Chaumont-Gistoux vlag.svg |
| Arrondissement: | Nivelles |
| Nis: | 25018 |
| Mayor: | Luc Decorte (ARC) |
| Postal-Codes: | 1325 |
| Telephone-Area: | 010 |
| Web: | www.chaumont-gistoux.be |
| Coordinates: | 50.6769°N 4.7196°W |
Chaumont-Gistoux (in French pronounced as /ʃomɔ̃ ʒistu/; Walloon: Tchåmont-Djistou) is a municipality of Wallonia located in the Belgian province of Walloon Brabant. On 1 January 2006 Chaumont-Gistoux had a total population of 10,926. The total area is 48.09 km2 which gives a population density of 227 inhabitants per km2.
It was formed from the fusion, in 1977, of Dion-Valmont (itself a fusion in 1971 of Dion-le-Val and Dion-le-Mont), Bonlez, Corroy-le-Grand, Longueville and Chaumont-Gistoux. The administrative offices are now in the village of Gistoux.
It is a semi-rural municipality with several working farms, large areas given over to fields and forests, although there is a major industry of sand extraction, now mostly in decline. Due to this history there are now several haulage and construction firms based in the municipality.
Chaumont-Gistoux is on the KW-line, a defensive line erected early in the Second World War, intended to prevent invasion from Nazi Germany. A small museum houses information about the line and many exhibits from the war.
Princess Claire of Belgium grew up in Chaumont-Gistoux. The Coombs family still resides there to this day, and the Princess, her husband Prince Laurent and their children are often seen in the municipality.
Bonlez, Chaumont, Corroy-le-Grand, Dion-le-Mont, Dion-le-Val, Gistoux, Longueville and Vieusart or (Vieux-Sart).