Remember, Gronk became the new 24/7 champ after beating up on Mojo Rawley at WrestleMania 36 last month ... pinning his friend to take over the shiny, new belt.

While it seemed like it was the beginning of a full-on career with Vince McMahon's org, the 30-year-old would end up BACK in the NFL weeks later to join his bestie, Tom Brady, on the Tampa Bay Buccaneers.

So ... what's Gronk gonna do with his belt??

HE'S DEFENDING THE DAMN THING, BABY!!!!

Rob joined his brother, Chris, on his "Gronk'd UP" podcast to discuss the status of his championship ... and he makes it clear he's got his eyes peeled for anyone looking to steal his belt -- even Bucs head coach Bruce Arians.

"Imagine coming out of the meeting room, I'm like looking to my left down the hallway ... looking to my right to make sure no one is out of the meetings yet, and then all of a sudden ... Coach Arians just comes out of nowhere with a flying elbow and takes me out and pins me and becomes the 24/7 champ," Gronk says.

"That would be legendary. That would be an honor to lose to him."

Of course, the point of the 24/7 belt is ANYONE can come out of nowhere to try to take it from Gronk ... and he says he's gonna have a huge target on his back once the coronavirus pandemic is over.

Gronk even speculates someone could try taking it from him DURING AN NFL GAME ... but he's up to the challenge.

"So many different people coming at me from all angles."