Part of the west side is the Osuzu Mountains, and the rest is a river terrace that approaches the coast of the Hyūga Sea.

The hilly area that occupies much of the town is arid, and remained largely undeveloped for many years until full-scale development began after World War II.

Miyazaki Prefecture Kawaminami has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

During the Edo period, During the Meiji period, the ex-samurai of Takanabe Domain built irrigation canals to develop new rice fields, and large-scale farm development was carried out by gathering farmers from inside and outside the prefecture, but most of the area remained undeveloped, and there were constant conflicts over water.

The village of Kawaminami within Koyu District, Miyazaki was established on April 1, 1889 with the creation of the modern municipalities system.