Achernar Prime was a planet located in the space of the galaxy's Beta Quadrant, in orbit of the Achernar star system. In the late 24th century, Achernar Prime became the capital planet of the Imperial Romulan State.

Until December of 2379, it was a planet in the Romulan Star Empire and amongst the Star Empire's chief farming worlds; a fleet loyal to Donatra took control of the planet that year, and from there Donatra declared the Imperial Romulan State's existence. (ST novel: Articles of the Federation)

In 2381, Benjamin Sisko commanded the Federation starship USS Robinson on a mission to Achernar Prime and met with Donatra. (ST - Typhon Pact novel: Rough Beasts of Empire)