Floyd Mayweather Flashes $300 Million Smile after Fight Announcement

Floyd Mayweather stepped out in Hollywood Wednesday night ... as the RICHEST ATHLETE TO EVER WALK THE EARTH!

Hours after the big McGregor vs. Mayweather announcement, Floyd hit up the "All Eyez On Me" movie premiere in Westwood lookin' like a million bucks (times 300).

Mayweather spoke with our friend, Robert Littal at BSO, during the premiere -- and had a message for Conor and his fans.

Floyd has said he expects to make between $200 and $300 million for the McGregor fight -- though he hasn't confirmed the terms of the deal yet.

We spoke with Dana White who says Conor should rake in around $100 mil.

Popcorn on Floyd, right?!