"From the International Space Station: I voted today," a post attributed to Rubins that was published by the NASA Astronauts Twitter page, read.
A photo showing a curtained off part of the space station containing a sign with the text "ISS Voting Booth" accompanied the post.
Rubins arrived at the ISS on 14 October, along with Russian cosmonauts Sergei Ryzhikov and Sergei Kud-Sverchkov.
From the International Space Station: I voted today— NASA Astronauts (@NASA_Astronauts) October 22, 2020
— Kate Rubins pic.twitter.com/DRdjwSzXwy
The crew, which is scheduled to remain at the ISS until April 2021, has been tasked with repairing an air leak in the Russian Zvezda module of the space station.
Voting in the upcoming US presidential election, which sees incumbent Donald Trump take on Democrat Joe Biden, will close on 3 November.