The American Gangster was slapped with 5 battery citations after an alleged brawl at a Las Vegas hotel the night of December 18 ... where Sonnen was accused of roughing up numerous people.

However, a judge in Nevada dismissed all 5 misdemeanor battery charges against Chael on Thursday.

"This matter was dismissed by the court on its own based upon the fact that the citation’s notice to appear failed to comply with the legal requirements as set forth by Nevada law," the Clark County District Attorney told us when we asked for an explanation.

It's important to note, the 5 citations were dismissed "without prejudice" ... meaning the state can refile the charges if they choose.

For his part, Sonnen's been mum ... opting not to address the incident.

Despite laying down his gloves in the Bellator cage back in June 2019, Chael's as popular as ever ... becoming one of the most respected MMA analysts in the world.

As a fighter, Sonnen was one of his era ... beating Rampage Jackson, Wanderlei Silva, Shogun Rua, and Michael Bisping.