Former wrestling champ Matt Hardy was kicked out of court-ordered rehab today for failing a breathalyzer test ... this according to multiple sources.

Earlier this year, Hardy was ordered to go to rehab by the court after a string of run-ins with the law.

We're told the staff at the rehab got suspicious of Hardy's behavior on Friday and gave him a breathalyzer test on the spot ... which he failed. According to our sources, Hardy was adamant he wasn't drinking ... and said he only failed because he had "just used mouthwash."

The staff wasn't convinced and gave Hardy the old heave-ho from the facility.

Back in September, the Moore County DA said if Hardy didn't comply with the treatment, he would be put in jail on a million dollar bond. We're told Hardy still had about a month to go before he was through.