The singer says she was left feeling 'shaken' for days after the bizarre encounter which took place while she was driving through California with a pal.
The 28-year-old opened up about the extra-terrestrial experience during a 2020 piece for Interview magazine alongside fashion designer Rick Owens.
As the pair got talking, the subject of Area 51 - and alien life forms - came up, with Owens saying that it would be 'a little arrogant' to think there's 'nobody else but us' in the universe.
Cyrus was quick to agree, adding: "That's what I f*****g think!"
She went on to reveal her own UFO encounter that left her 'f****d up' after she was 'chased' by a 'flying snow plough' that was hurtling through the night sky. Sounds pretty scary to me.
Cyrus said: "I had an experience, actually.
"I was driving through San Bernardino with my friend, and I got chased down by some sort of UFO.
"I'm pretty sure about what I saw, but I'd also bought weed wax from a guy in a van in front of a taco shop, so it could have been the weed wax.
"But the best way to describe it is a flying snow plough.
"It had this big plough in the front of it and was glowing yellow. I did see it flying, and my friend saw it, too. There were a couple of other cars on the road and they also stopped to look, so I think what I saw was real."
Cyrus said the experience rattled her so much that she 'couldn't really look at the sky the same', fearing 'they might come back'.
She added: "I was shaken for, like, five days. It f****d me up."
Despite feeling distressed by what she saw, interestingly Cyrus said she didn't feel threatened by the 'UFO', agreeing with Owens by saying it's a 'form of narcissism' to think humans are the only things that could be in this universe.
"I didn't feel threatened at all, actually," she said.
"But I did see a being sitting in the front of the flying object.
"It looked at me and we made eye contact, and I think that's what really shook me, looking into the eyes of something that I couldn't quite wrap my head around."
I can just picture some aliens rocking out to 'Party in the USA' right now.
Wonder if any of them have tried to re-enact the 'Wrecking Ball' video yet?