Archeological finds show the area to have been inhabited for about 5,000 years, similar to its neighbouring municipalities around Lake Mälaren.

Besides graves from the Stone Age, there is also an interesting runestone that can be visited that is listed in the Rundata catalog as Sö 338.

A newer sight is the Taxinge-Näsby Castle, which was begun sometime in or before the 14th century, by Bo Jonsson Grip.

This is a demographic table based on Nykvarn Municipality's electoral districts in the 2022 Swedish general election sourced from SVT's election platform, in turn taken from SCB official statistics.

The results of the Sweden Democrats were not published by SCB between 1988 and 1998 at a municipal level to the party's small nationwide size at the time.

Blocs This lists the relative strength of the socialist and centre-right blocs since 1973, but parties not elected to the Riksdag are inserted as "other", including the Sweden Democrats results from 1988 to 2006, but also the Christian Democrats pre-1991 and the Greens in 1982, 1985 and 1991.