UCLA hoops star Amari Bailey signed a lucrative 'NIL' deal with Ethika and will receive a percentage of revenue from his products ... TMZ Sports has learned.

The exact details of the deal remain unknown, but the California-based apparel company tells us the plan is for Amari to create/design underwear with the company.

"The NIL deal with Amari couldn’t have come at a better time. I’ve followed Amari’s career since he was a youngster," Ethika exec Darius Burton tells us.

"I’ve always been impressed how he handles himself on and off the court. When I heard he was making the move to Southern California, I wanted to figure out a way to work with him."