Koshigaya has a Humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

Koshigaya-shuku prospered during the Edo period as a post station on the Nikkō Kaidō and the Ōshū Kaidō highways, and the town served as the temporary residence of the Tokugawa shōgun after the 1657 Great Fire of Meireki which destroyed Edo Castle.

Koshigaya has a mayor-council form of government with a directly elected mayor and a unicameral city council of 32 members.

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

JR East – Musashino Line Tōbu Railway - Tōbu Isesaki Line The actual scenery of Koshigaya is set in the anime and manga series, Miss Kobayashi's Dragon Maid.