2:34 PM PT -- Janelle Brown just addressed Garrison's death, taking to social media to post a photo of her boy and writing ... "Kody and I are deeply saddened to announce the loss of our beautiful boy Robert Garrison Brown. He was a bright spot in the lives of all who knew him."

She adds, "His loss will leave such a big hole in our lives that it takes our breath away. We ask that you please respect our privacy and join us in honoring his memory."

Janelle Brown's son, Garrison, has died ... and it appears his death is a suicide, TMZ has learned.

The "Sister Wives" star -- who's appeared alongside his mother and father, Kody Brown, on the hit TLC series over the years -- passed away Tuesday in Flagstaff, AZ ... where he had his own home after having moved away from his family.

Flagstaff PD tells us ... officers responded to Garrison's home Tuesday morning on a report of a death, and when they arrived -- they discovered him dead at the scene. We're told Garrison appears to have suffered a self-inflicted gunshot wound.

We're told no foul play is suspected, and for now ... police are looking into this as an apparent suicide. FPD says Garrison's brother Gabriel arrived at the house and found him there. No word on whether a note was left behind ... we're told an investigation is underway.

Garrison has appeared on "Sister Wives" since it first aired on the network way back in 2010 -- when he was just a kid. The series chronicles his dad's polygamous lifestyle in Utah, where Kody has multiple wives ... Janelle was one of them until they got divorced last year.

As for Garrison ... he's one of Kody's many children, and has several siblings and half-siblings -- many of whom are also featured on the show. All in all, he's Kody and Janelle's fourth child. He has 5 direct siblings, and two other half-siblings from different marriages.

While he and his family lived in Utah at first, they eventually moved to Vegas -- and as he came of age, Garrison showed an interest in enlisting in the armed services. While he wanted to join the Army ... Garrison ended up signing up for the National Guard.

Garrison moved out of his parents' house a few years ago during the pandemic -- this amid a massive feud within the family over COVID and the strict rules Kody was enforcing.

In the end, Garrison ended up buying his own home in Arizona and has lived there since 2021. The guy was pretty active on social media as well ... documenting his life and pets.

His last post on Instagram features him with a new cat he said he'd welcomed into the household ... a feline he called Ms. Buttons. He described the cat this way, "Newest edition to my home, Ms Buttons. She’s 9 years old and was on the line for euthanasia but my savior complex couldn’t suffice."

It's an absolute tragedy for his loved ones -- especially for Janelle, who just announced she recently experienced a cancer scare and had to have two pre-cancerous spots removed.

Garrison is survived by many family members and loved ones. He was only 25.

RIP

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