Halsnæs Kommune is a municipality (Danish, kommune) in Region Hovedstaden ("Capital Region"). The municipality covers an area of 122.15 km² (2013), according to Municipal Key Figures (De Kommunale Nøgletal (www.noegletal.dk)), and has a total population of 30,644 (1 April 2014). Its name comes from Halsnæs, the peninsula that forms the western part of the municipality.
The municipality was created on January 1, 2007 as a merger of the former municipalities of Frederiksværk and Hundested. At first the merged municipality wore the hyphenated name Frederiksværk-Hundested, but it was changed to Halsnæs on January 1, 2008. Its mayor as of 1 January 2014 is Steen Hasselriis, a member of the Venstrepolitical party.