Cardi B Performs in Bathrobe at Bonnaroo After Outfit Splits

Cardi B's rainbow-colored jumpsuit couldn't take the pressure of a full concert worth o' booty shaking, but she made sure the show went on ... slightly more covered up.

The rapper had just taken the stage Sunday night at the Bonnaroo Arts and Music Festival when -- a couple songs into her set -- she suffered a wardrobe malfunction ... a split right down the middle of her ass.

Cardi left for a few minutes after announcing her outfit had ripped, but after the crowd entertained themselves by singing "Old Town Road" ... she reemerged in a white bathrobe and declared, "We gonna keep it moving, baby."

Even with her setback, Cardi's set was a super quick 45 minutes, but was jam-packed with all of her hits ... including "I Like It," "Money" and "Bodak Yellow" to close it out. She also vowed to "keep it sexy" and managed to do so ... even in a robe.

As we reported, Cardi's had to cancel some shows lately due to complications with her recovery from cosmetic surgery -- lipo and a boob job.