EXCLUSIVE

Ex-UFC star Mayhem Miller was arrested again -- this time for vandalizing a tattoo shop -- and officials have set his bail at a whopping $1 MILLION ... TMZ Sports has learned.

Miller -- who's previously been arrested for DUI, fighting cops and domestic violence -- was taken into custody Tuesday stemming from an incident back in January when officers say the 35-year-old vandalized the ink shop in Orange County, CA with graffiti.

According to court docs, obtained by TMZ Sports, Miller's bail was set at $1,000,000!!!!!

We're told the number is so high because Miller was out on bail at the time for a previous felony and has a deep, DEEP criminal record.