What is the homeworld of the Romulans?

The homeworld of the Romulans is Romulus.

Romulus is the principal homeworld of the Romulans in the Star Trek universe. It belongs to the Romulan system and has a sister planet, Remus, which is associated with the Remans. Romulans and Vulcans share a distant ancestry, but their civilizations separated after ideological conflict: Vulcans embraced Surak’s teachings of logic and emotional discipline, while the Romulan ancestors rejected that path.

The Romulans first appeared in the original-series episode “Balance of Terror,” where their resemblance to Vulcans was revealed to the audience. That connection became an important part of Star Trek’s political and cultural history. Romulus is often linked with secrecy, military power and the Romulan Star Empire, whose relations with the United Federation of Planets are frequently hostile or uneasy.

A major later development is that Romulus was destroyed by a supernova in the 2009 Star Trek film’s timeline, an event that also shapes the background of Star Trek: Picard. That destruction does not change the canonical answer to the question: Romulus remains the Romulans’ homeworld, even though its fate differs across timelines and stories.