Chance the Rapper's bodyguard allegedly unleashed some WWE moves on a guy right in front of the MC ... and the whole thing was caught on surveillance video.

Law enforcement sources tell TMZ ... Chance's private security guard, 44-year-old Star Thomas, was arrested Thursday night at the W Hotel in Chicago after he allegedly body slammed a man in the lobby. We're told Chance had a front row seat as it all went down.

The alleged victim was trying get into the same elevator as Chance and his crew around 9 PM, according to our sources ... and the bodyguard blocked him. We're told about 2 hours later they ran into the man again in the lobby, and that's when Thomas threw him down.

Chance's bodyguard was booked for misdemeanor simple battery. We've reached out to his camp for comment ... so far, no word back.

We spoke with Thomas's lawyer, Elias R. Hilal, and he tells us Thomas was not the aggressor. According to Hilal, the altercation started when the alleged victim "shoulder hit" Thomas and mouthed off. That's when Chance's bodyguard grabbed the guy. Hilal adds that Thomas never took the alleged victim to the ground.