By TMZ Sports

Former four division world champion Adrien Broner will not be prosecuted for allegedly pulling a gun on a man and violently robbing him earlier this year ... TMZ Sports has confirmed.

A jury trial was scheduled to begin Wednesday, but according to a Hamilton County court clerk, the prosecutor's witness was a no-show ... so the judge dropped the charges.

Broner was present in court with his lawyer. AB is completely off the hook in this case -- the alleged victim dropped his civil suit against him a few months ago.

Broner was released from custody last month, after serving a court ordered 30-day jail term for appearing about three hours late for a July 19 court date.

Hamilton County Common Pleas Judge Robert Ruehlman had previously found Broner in contempt of court for the late appearance and handed down the 30-day punishment.

According to the claims that were made by the victim,  Broner pointed a handgun, knocked him unconscious and robbed him - after losing thousands of dollars during a few games of high stakes bowling.

Broner has been out of the ring since an April stoppage win over Ashley Theophane in Washington, D.C. Broner failed to make the 140-pound limit for the contest, which caused him to lose his WBA junior welterweight title on the scale.