Millyz has a score to settle with Machine Gun Kelly, but has no idea when they'll get it cracking ... because he thinks Kelly's secretly scared of him.
The Massachusetts-bred rapper tells TMZ Hip Hop he didn't get into the biz to create a white rapper beef sideshow ... but claims MGK has worked his last nerve, and been working overtime behind the scenes to make sure he doesn't get any of his looks.
Millyz says he didn't appreciate MGK's unprovoked "Renegade" shot at Jack Harlow -- especially after experiencing what he says were "weird" encounters in person.
For years, Millyz says MGK has faked like he doesn't know who he is, and accuses him of gatekeeping over threats he'll become more popular.
The fight for streams may be slim pickings, but Millyz tells us he's been able to make his dough in spite of the alleged blackball attempts from MGK.
Millyz just released his new album titled "Holy Water" ... but he really sounds bent on dragging MGK through hell.