Holbæk municipality is a municipality (Danish, kommune) in northeastern Region Sjælland on the island of Zealand (Sjælland) in Denmark. The municipality includes the island of Orø, and covers an area of 583 km², and has a total population of 69,010 (2008). Its mayor for 2010–2013 is Søren Kjærsgaard, a member of the Liberal Party (Venstre) political party. The main town and the site of its municipal council is the city of Holbæk. On January 1, 2007 Holbæk municipality was, as the result of Kommunalreformen ("The Municipal Reform" of 2007), merged with existing Jernløse, Svinninge, Tornved, and Tølløse municipalities to form a new Holbæk municipality.

The ten largest urban areas in the municipality are:

Holbæk from the air