Floyd Mayweather Jr. is as single as a dollar bill right now…

The boxing champ and his “ex-fianceé” Shantel Jackson have called it quits after being together off-and-on for 4 years.

Floyd proposed back in 2013 and surprised Jackson with $10 million diamond rock, but things have since gone sour between the two, and  Shantel’s rep confirmed the news to TMZ Sports over the weekend that the couple are no longer together.

“Miss Jackson has moved on with her life from Floyd and is saddened that she has had to deal with many problematic and dramatic situations from the media since their break up.”

Jackson’s rep says Shantel’s Instagram account was mysteriously shut down in the wake of the split — and she suspects it was a hit job from someone she knows personally. We’re told Shantel is currently trying to get her account up and running again.

As for what happened to the $10 million engagement ring — so far, no word on what happened to it.

Her Instagram account now appears to be up and running — she posted this photo Friday (Apr 11) with the caption: “Because I’m Happy…..”

…But still no word on that $10 million ring, which we doubt she’s really going to give up willingly.