Daniel Cormier upheld a long running wedding tradition by tossing his wife's garter at their wedding reception ... and his pal Luke Rockhold walked away the winner. 

Daniel got slow and sexy while he removed the garter of his bride, Salina, during Saturday's party.

It hit the floor, but an anxious Luke scooped it up and waived the prize.

As we reported ... Dana White wasn't invited to the wedding, but we're told there's no beef between the 2. Here's hoping his boss still sent a gift

Congrats!