'Mayhem' Miller Charged W/ Felony Assault, Battery, For Alleged Bar Fight

Jason "Mayhem" Miller, troubled MMA fighter, has been charged with 2 felonies -- assault and battery -- for his alleged involvement in a bar fight where he's accused of breaking another man's ribs, TMZ Sports has learned.

We broke the story ... 40-year-old Miller was allegedly involved in a brawl outside a San Fernando Valley bar in early September. The man Mayhem is accused of hitting initially decided not to file a police report ... however, changed his mind after going to the hospital, where he was diagnosed with cracked ribs.

Earlier this week, officials decided to charge Miller with felony assault and felony battery ... charges that could carry years behind bars, if convicted.

The two felonies aren't the only charges Miller is contending with ... he was recently arrested for felony domestic violence after allegedly roughing up his girlfriend.

Miller -- who hasn't fought in the UFC since 2012 -- last fought professionally in 2016 ... losing his last fight via a rear-naked choke.