Næstved Municipality (Danish: Næstved Kommune is a kommune in the Region Sjælland on the island of Zealand in the south of Denmark. The municipality includes the island of Gavnø. It covers an area of 681 km2, and has a total population of 84,574. Its mayor is Carsten Rasmussen, a member of the Social Democrats political party. The main town and the site of its municipal council is the town of Næstved.

Zealand at 7,031 km2 is the largest and most populous island in Denmark proper. Zealand had a population of 2,319,705 on 1 January 2020, comprising 40% of the country's population.