Treach & Pepa's Daughter Egypt Gets Engaged With Cameras Rolling

"Growing Up Hip Hop" just hit a big milestone -- Treach and Pepa's daughter is officially tying the knot with her BF ... despite some of her friends and family's on-screen objections.

The rap couple's only kid, Egypt, was performing early Saturday morning at WeHo's Whiskey a Go Go alongside her reality TV beau, Sammattick -- a fellow MC himself. In footage obtained by TMZ, you can see Sam pop the question in front of a packed house.

Spoiler alert ... she said yes!!! Another spoiler alert ... we're told cameras were rolling during the onstage engagement, so this is definitely gonna be featured in the upcoming 5th season of the show.

Here's why the proposal is kind of a big deal in the 'GUHH' world -- Egypt and Sam almost had themselves a shotgun Vegas wedding last year, which Egypt's entire inner circle rushed to halt at the very last minute ... and seemed very much so against.

Pepa doesn't seem to like the dude all that much either, suggesting there are red flags about him that Egypt isn't necessarily seeing herself. Talk about sticking it to your mom, right?

There was also a potential love triangle problem that got teased in the season 4 finale a few months ago, with rapper Lil Twist showing some interest in Egypt ... right in front of Sam, no less.