Emergency services were called to an altercation between two groups - one believed to be American hip-hop duo Rae Sremmurd and their entourage - on Federal St in downtown Auckland shortly after 4pm.
In the footage, obtained by TMZ, Jxmmi is seen on the ground wrestling with several people, including a woman, while punches are thrown. Witnesses say they heard a bottle break in the skirmish and saw someone wielding it as a weapon.
There's no indication of who did the stabbing or who got stabbed.
Slim Jxmmi was later seen talking to police, but so far no arrests have been made, according to TMZ.
In another video posted to the rapper's Instagram last night, Jxmmi showed off a bandaged hand as he said, "Ice on my wrist".
A man had allegedly been stabbed with a glass bottle and was transported to hospital.
Detective Senior Sergeant Kathryn Bostock says two men are assisting police with enquiries, however the investigation is ongoing.
Rae Sremmurd are scheduled to appear at Australia's FOMO Festival over the weekend.