Rapper Busta Rhymes is facing multiple assault charges after an alleged altercation with his assistant ... TMZ has learned.

Law enforcement sources tell TMZ ... Busta got into a verbal argument that allegedly turned physical last Friday ... where he faced off against a 50-year-old man who works for him.

We're told the argument, which took place around 10 in the morning in Brooklyn, escalated and resulted in Busta punching his assistant on the left of his face.

Sources tell us ... Busta took off after the alleged assault, prompting the assistant to call 911. Police and paramedics soon arrived on the scene and took Busta's assistant to a nearby hospital.

We're told Busta turned himself in to the police earlier this week on Tuesday and was given a desk appearance ticket ... which means the rapper will be heading to court over the incident.

The "Touch It" artist has been charged with misdemeanor assault in the 3rd degree, attempted assault, and harassment ... according to our law enforcement sources.

We've reached out to Busta's rep for comment ... so far, no word back.