Alexis Eddy -- who rose to fame on MTV's "Are You The One?" -- has been found dead in West Virginia ... TMZ has learned.

Law enforcement sources tell TMZ ... cops got a call just before 7AM Thursday morning for a female in cardiac arrest. We're told no foul play is suspected, but authorities are still waiting on a toxicology report to determine cause of death.

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A West Virginia native, Alexis was a contestant on the reality dating show back in 2017, and she caused quite a stir in the house for her character and backstory, revealing on-camera her cousin is a convicted murderer.

Alexis was very open on social media about her struggles with substance abuse ... but as recently as late September she said she and her father were both clean and sober. She also posted pics comparing the 2 in a side-by-side from a couple years ago.

Guuuuuys look at this pic of me n my daddio finally sober together 😭😭😭 pic on the right was two years ago... what a difference.

So very blessed today.#RecoveryRocks pic.twitter.com/0J8sIY8Duc — Alexis Eddy (@lexoquence) September 28, 2019 @lexoquence

A family member tells us Alexis came home to her mom's house Wednesday night around 11 PM and seemed to be fine. She was found by another family member ... and they believe she was still sober.

In October of 2019, Alexis announced she was engaged, but it appears that engagement was recently ended.