The man who viciously attacked comedian Steve Brown onstage has been arrested ... TMZ has learned.

Marvin Toatley was arrested Wednesday in Columbia, South Carolina and booked on 3 counts of assault and battery of a high and aggravated nature, as well as one count of third degree assault and battery ... and one count of malicious injury to property.

Cops say their fugitive task force found Toatley at an apartment complex. He's still in custody.

As we reported ... Toatley hopped onstage in the middle of Steve's set Sunday and started swinging a mic stand^[1] like a sword. Cops say 4 people in total were injured from his outburst. 

Steve told us the guy was laughing^[2] it up before coming after him, seemingly out of nowhere.