Tony Raines -- an MTV reality TV star -- was arrested early Sunday morning for operating a vehicle while intoxicated ... TMZ has learned.

Raines -- a contestant on "The Challenge" and "Real World: Skeletons" -- was arrested on 1 count of operating a vehicle while intoxicated, 1 count of reckless operation and four counts of negligent injuring.

It's unclear exactly what led to his arrest ... but, sources tell us Raines was at a  wedding in Hammond, Louisiana on Saturday night and he went to the afterparty at a nearby restaurant after.

At the restaurant, Tony was allegedly upsetting people ... and, he allegedly ended up getting into it on the dancefloor with another guy.

We're told the other guy threw a fist at Raines ... and, then Raines stormed out and drove off. He was arrested elsewhere sometime after this all allegedly went down.

Tony's being held on $7,500 bond ... and, jail records say he's still awaiting arraignment at the time of this story being published.