Floyd Mayweather, Mookie Betts, and a gang of other star athletes and actors rubbed shoulders at a swanky party in Los Angeles Wednesday night ... where the 50-0 fighter delivered an emotional speech to the famous partygoers!

In addition to TBE and the 8x All-Star, Draymond Green, Terance Mann, Michael Porter Jr., Trevor Ariza, Meagan Good, and Jonathan Majors were also in the building.

As for why all the stars came out ... it was to celebrate the launch of Hidden Empire Sports, a collaboration between The Union and EAG Sports Management, and created by Deon Taylor.

One of the evening's highlights came when 47-year-old Mayweather received an award for his contributions to sports and entertainment, where he spoke about his ambition to be the greatest.

"I had a dream. I had a goal to be the best. My goal was to just be the best," Floyd told the audience, before talking about the importance of fathers.

"My dad is remarkable, unbelievable trainer, and I really got to take my hat off to my father. Me and my dad through rain, sleet, snow and hail, he believed me in. He truly, truly believed in me. And we need more Black fathers like my father."

Gil Robertson, president of the African-American Film Critics Association (AAFCA), also honored Draymond and Mookie.

The crowd was also treated to a trailer of Mayweather's upcoming documentary, "The GOAT," as director Deon Taylor and producer Roxanne Avent Taylor debuted the preview for the first time.

We broke the story in late 2022 ... Floyd and the Taylors were working on a "Last Dance" style doc highlighting the undefeated boxer's ascension to the top of the sports world.

"I just feel the world should see a different part of Floyd Mayweather. I think the people should see a different part of me," Floyd told us at the time.

Back to the Wednesday night shindig ... L.A.'s always a star-studded town, but especially this week, as loads of athletes have flooded the city to attend Thursday's ESPY Awards.