Daniel Cormier just penned a goodbye to the UFC ... thanking all his fans and coworkers in a heartfelt note -- and it's pretty freakin' emotional.
The 41-year-old had said in the buildup to UFC 252 that it would be his final match ... and in a statement Monday -- 2 days after he dropped his second straight bout to Stipe Mioicic -- he appeared to officially hang up his gloves.
"Thank you all for the love and support," D.C. wrote. "Not what I wanted or expected but it is what it is.