Floyd Mayweather's 40th Birthday Bash Featuring Mariah, Bieber (PHOTOS/VIDEO)

Floyd Mayweather was true to larger-than-life form Saturday night, celebrating his big 4-0 with about a million celebs.

The bash went down at the J.W. Marriott at L.A. Live. Mariah sang Happy Birthday, Justin Bieber followed with "Where are U Now" as Too Short, Nicole Murphy, The Game, Bobby Brown, Adrien Broner, Terrell Owens, Fat Joe and others looked on.