Post stations located within the borders of modern Annaka were: Itahana-shuku, Annaka-shuku, Matsuida-shuku and Sakamoto-shuku.

Annaka Town was created within Usui District, Gunma Prefecture on April 1, 1889, with the creation of the modern municipalities system after the Meiji Restoration.

On March 1, 1955, Annaka merged with neighboring Haraichi, Isobe and Itahana towns, and Higashiyokono, Iwanoya, Akima and Gokan villages.

Annaka has a mayor-council form of government with a directly elected mayor and a unicameral city council of 20 members.

In terms of national politics, the city is part of Gunma 5th district of the lower house of the Diet of Japan.