| Zemst | |
| Picture-Legend: | Town hall of Zemst |
| Map: | Zemst Flemish-Brabant Belgium Map.svg |
| Map-Legend: | Location of Zemst in Flemish Brabant |
| Arms: | Zemst wapen.svg |
| Flag: | Zemst vlag.svg |
| Arrondissement: | Halle-Vilvoorde |
| Nis: | 23096 |
| Mayor: | Veerle Geerinckx (N-VA) |
| Majority: | N-VA, VLAM, Groen, Vooruit |
| Postal-Codes: | 1980–1982 |
| Telephone-Area: | 015, 02, 016 |
| Web: | www.zemst.be |
| Coordinates: | 50.9833°N 32°W |
Zemst (in Dutch; Flemish pronounced as /zɛmst/) is a municipality located in the Belgian province of Flemish Brabant. The municipality comprises the villages of Elewijt, Eppegem, Hofstade, Weerde, Zemst-Laar, Zemst-Bos and Zemst proper. On January 1, 2006, Zemst had a total population of 21,327. The total area is 42.83 km2 which gives a population density of 498 inhabitants per km2.