Jake Paul and Eddie Hearn Make $1 Million Bet on Serrano-Taylor Fight

Jake Paul's bet with Eddie Hearn for this weekend's matchup between Amanda Serrano and Katie Taylor will NOT involve any tattoos -- just a million freakin' dollars!!

It all went down during the final presser for the huge fight going down this Saturday at Madison Square Garden ... with Hearn igniting the wager after he asked Paul about his fighter.

"You're fully confident that your charge will be victorious and become undisputed lightweight world champion?" Hearn asked Paul on Friday.

Of course, JP doubled down on his belief Serrano will come out on top -- and that's when the 25-year-old boxer placed his bet.

"I got a bet for you Eddie," Paul said. "I bet you all the jewelry that I'm wearing right now that Amanda wins the fight."

Hearn hit him back with a couple of jokes ... saying "10 grand is not a lot" -- but Paul insists his diamond chain is worth $500k!

"Maybe we can talk a million," Hearn replied ... and the two shook hands.

Of course, Paul is known for making bets when it comes to the boxing ring -- remember, Tyron Woodley had to get an "I Love You Jake Paul" tattoo after he lost to the 5-0 boxer last August.

The $1 million bet ain't the only big-money deals being made this week ... the two female boxers' purse will be more than that, Paul previously said.

"This is just historic for the sport in general."