CM Punk -- I Got Fired From WWE ... ON MY WEDDING DAY!

Former WWE Champ CM Punk claims he never quit the famous wrestling company ... he was FIRED -- and it all went down on his wedding day.

Punk spoke out on the Art of Wrestling podcast with Colt Cabana for the first time since walking out on the company in January ... and went into extreme detail about why he left.

The wrestling star says he never technically quit ... he got the 'ole heave ho -- delivered in the mail on his wedding day to WWE Diva AJ Lee.

The whole interview is almost 2 hours long -- Punk talks about wrestling with a staph infection for months ... and how he threatened to sue the company over royalty payments.