We're told Lopez will be the emcee of the November 28 fight ... introducing the various fighters and tossing to musical acts throughout the evening.

In other words, it's not just a fight ... it's an event.

Sources tell us Lopez will be at the fight venue -- not hosting remotely -- and the production is already taking steps to make sure they adhere to COVID-19 regulations.

Lopez -- along with all of the fighters, trainers, production crew, etc. -- will most likely undergo rigorous testing leading up to the fight to ensure everyone is safe and healthy.

As for the musical acts, we're told producers are gunning for A-list talent and have superstars from the R&B and the hip-hop world lined up ... now it's just about finalizing the contracts.

The event is being put on by Triller -- which is looking to dethrone TikTok as the go-to place for music-driven social media -- so it's obvious why the entertainment portion of the night is so important to them.

As for Lopez, he's a hardcore combat sports fan whose been regularly training at Freddie Roach's Wild Card Boxing Gym in L.A. for years.

"I have the opportunity to combine my passions for boxing with hosting is truly a career milestone, and for it to be at such a legendary event, this is a once in a lifetime opportunity and I couldn't be more proud to be a part of it," Lopez said in a statement to TMZ Sports.