Hvalsø
| Kirke Hvalsø | |
|---|---|
| Town | |
| Skjoldenæsholm south of town | |
| Coordinates: 55°35′39″N 11°51′34″E / 55.59417°N 11.85944°E | |
| Country | Denmark | 
| Region | Zealand (Sjælland) | 
| Municipality | Lejre Municipality | 
| Area | |
| • Urban | 2.5 km2 (1.0 sq mi) | 
| Population  (2025) | |
| • Urban | 4,877 | 
| • Urban density | 2,000/km2 (5,100/sq mi) | 
| • Gender | 2,329 males and 2,548 females | 
| Time zone | UTC+1 (CET) | 
| • Summer (DST) | UTC+2 (CEST) | 
| Postal codes | 4330 | 
Hvalsø is a town and a former municipality (Danish, kommune) in Region Sjælland on the island of Zealand (Sjælland) in east Denmark. The former municipality covered an area of 72 km2, and had a total population of 7,856 (2005). Its last mayor was Virginia Holst, a member of the Venstre (Liberal Party) political party. She was the first foreign national becoming mayor in a Danish municipality.