Nasukarasuyama is located in the center-eastern part of Tochigi Prefecture, at the western foot of the Yamizo Mountains, at the southern end of the Shiona Hills, and in the middle reaches of the Naka River.

Nasukarasuyama has a Humid continental climate (Köppen Cfa) characterized by warm summers and cold winters with heavy snowfall.

The modern city of Nasukarasuyama was established on October 1, 2005, from the merger of the towns of Karasuyama and Minaminasu (both from Nasu District).

Nasukarasuyama has a mayor-council form of government with a directly elected mayor and a unicameral city assembly of 17 members.

In terms of national politics, the town is part of Tochigi 3rd district of the lower house of the Diet of Japan.