The "Viva La Bam" star is making a return to the public eye after a rough few months and another trip to rehab, by signing on to be the celebrity ref for Chris Morgan's fight -- against another viral star TBD -- at the Showboat Hotel on September 7.

Bam inked the deal with fighting promoter Damon Feldman. Of course, both sides agreed to it BEFORE Margera went off the rails this weekend and berated a Southwest Airlines employee and got booted from a flight.

The next morning, Bam posted a series of videos on social media pleading for Dr. Phil to help him out because his "family is in shambles," and claiming his troubles are worse than ever. No word how all of this might affect the reffing gig.

Regardless, Morgan signed on for the event last month shortly after his bagel shop antics caught the attention of the entire internet ... for better or worse. Okay, probably worse.

Despite his recent drama, Margera's not God, nor is he Morgan's father or his boss ... so he should work out just fine as the referee of his match. (If you don't get that ... watch the vid ... it's worth it.)

It's unclear what Bam's getting paid to get in the ring and watch viral stars of new and old -- like Antoine Dodson, who's also on the fight card -- slug it out, but we're told Bagel Boss guy stands to make anywhere from 5 to 6 figures ... depending on ticket sales and online streams.

Fun fact -- Bam's father, Phil, has actually fought in Damon's boxing events in the past ... so the family has a history with his company.