Ray J is taking a 5-figure beating in court -- because a judge has ordered the singer to pay more than $26,000 ... after allegedly blowing off a radio appearance in South Carolina back in 2010.
The SC station -- called Cox Radio -- originally sued Ray J, claiming it paid him $20,000 to MC at a local event for a couple hours ... then attend a meet-and-greet with fans for another 30 minutes.
But according to the lawsuit, Ray blew the entire thing off -- and absconded with the money.
A South Carolina judge ruled in favor of Cox radio because Ray never showed up, awarding it $25,100 -- but Ray didn't pay, so Cox took the judgment to Ray's primary state of residence ... California.
The judgment has since swelled to $26,848.33. So far, no word back from Ray.