Cody Garbrandt Down To Fight Brandon Moreno, Promises KO Or Submission

Cody Garbrandt is ALL IN on a fight with Brandon Moreno ... telling TMZ Sports he wants a tilt with the champ, and he's promising a knockout or a submission when it happens!!

"No Love" broke it all down for us outside the Roosevelt Hotel on Friday ... saying he's been eyeing a move from bantamweight to flyweight for a while.

And, he tells us a fight with Moreno -- who just called Cody out this week -- is the perfect opportunity to finally make that happen.

"I'll finally get to fight at my natural weight [of 125 pounds] where I think I can perform my best," says Garbrandt, who tells us he's already started the process of changing around his diet and workout routine.

"I feel like I'm a way better fighter than him."

Don't get it twisted, though ... Garbrandt respects the hell out of Moreno -- telling us he believes the dude is a legit champion.

But, if the fight does get made ... Cody says he sees it all ending with him on top via some kind of finish.

"I'll finish him for sure," Garbrandt says. "KO, submission. Whatever."