Floyd Mayweather -- My $8 MILLION Night Out (VIDEO)

Floyd Mayweather was flexin' his bank account HARD Sunday night -- hittin' the streets with 4 INSANELY expensive cars and a $2 MILLION watch ... and TMZ Sports has the video.

Mayweather and his crew started the night at Staples -- where they sat courtside at the Lakers vs. Wizards game before hitting up Hyde Lounge on the Sunset Strip.

On the way out, Floyd called us over to give us a tour of his fleet ... starting with his $4.8 MILLION Koenigsegg CCXR Trevita.

He also rolled out his classic Rolls-Royce Phantom, his Rolls-Royce Drophead coupe and his Bentley Mulsanne.

So, how the hell does Mayweather afford to live like this??

The boxer says he'll be making $7 figures PER MONTH for the rest of his life thanks to "smart investments."

How was your Sunday night?