The Shire covers an area of 1,164 square kilometres (449 sq mi), and its seat of government is the town of Nungarin.

It was originally much larger, extending north into what is now the Shire of Mount Marshall until losing a section to that road board on 6 July 1923.

[2] In 1933, it included the Bonnie Rock, Campion, Lake Brown, Mukinbudin, and Wilgoyne districts, with an area of 1708 square miles.

In that year, it faced pressure to relocate the board seat to Mukinbudin as a more central location; however, instead, the Nungarin Road District was split into two and the Mukinbudin Road District formed on 1 September 1933, resulting in the Nungarin District losing over three-quarters of its land area.

The towns and localities of the Shire of Nungarin with population and size figures based on the most recent Australian census:[4][5] As of 2023, 64 places are heritage-listed in the Shire of Nungarin,[12] of which eight are on the State Register of Heritage Places, among them the Mangowine Homestead.