Cardi B's become a star this year, but we're still learning things about her ... like the fact she has an intense fear of heights.
The "Bodak Yellow" rapper got on top of the DJ booth around 2:45 AM at LIV Nightclub in Miami Saturday, but needed a helpful hand ... and then didn't let go.
As she put it ... "I'm a motha****in' gangsta but I'm afraid of heights so I'm gonna have this big motha****a hold my hand." Her bodyguard then did exactly that for her whole set -- check it out ... it's hilarious.
Cardi performed her huge hit along with "Motorsport" and "No Limit" ... all with hand-holding aide from her security guy. We're told at one point he also had to help pull down her dress.
Not a bad gig if you can get it.