Floyd Mayweather's first to the arena for his super-fight with Conor McGregor ... and he's DRIPPING in bling -- rockin' a fresh black and gold track suit.

Floyd partnered with world-famous fashion designer Philipp Plein for his robe and trunks with the same colors ... so we're pretty sure this is another Mayweather and Plein collab.  

Money's also got on his LeFerrari Hublot watch -- which is worth a cool $1 mil. 

Floyd seems pretty stoked to be in the building ... boogieing into T-Mobile with his TMT crew.

No sign of Conor yet ... but you know he's gonna be stuntin' just as hard.