Daniel Bryan: I'M RETIRING FROM WWE ... Here's Why

WWE superstar Daniel Bryan is officially DONE in the squared circle -- claiming he's retiring at 34 years old for medical reasons.

Bryan just issued a statement saying, "Due to medical reasons, effective immediately, I am announcing my retirement. Tonight on Raw, I'll have a chance to elaborate. #gratitude."

Bryan has talked about his medical issues in the past -- telling "Busted Open" he had concussion issues.

He has also praised WWE for protecting him by making him seek treatment from a barrage of specialists and preventing him from getting in the ring until he was cleared by doctors.

Now, with this announcement ... it doesn't appear he'll ever get the clearance and that might be why he's hangin' it up for good.

Story developing ...