Parnaroo is a rural locality in South Australia, situated east of Peterborough.

It shares the same boundaries as the cadastral Hundred of Parnaroo, which was established on 31 October 1878.

It was reportedly named for an Aboriginal word meaning "rain of little stones", which had been taken from a sheep run opened in the area in 1854.

Farmers at Parnaroo reported major challenges in the 1880s due to the landscape and low rainfall, being north of Goyder's Line.

[8] Parnaroo Post Office opened on 27 July 1871 and closed on 30 November 1916.