8:38 AM PT -- Jake Paul is going off on anyone who is still hating on his boxing career after the big reveal ... telling any naysayers to simply "shut the f*** up."

"Boxer true and true, better record than me, more wins by KO than me, same weight."

Of course, haters gonna hate ... so it sounds like that'll continue no matter what.

Jake Paul is sending a direct response to his haters with his next opponent -- he just announced he's slated to fight pro boxer Andre August next month.

The Problem Child is going up against a 10-1 cruiserweight fighter with five knockouts under his belt ... and he's referring to the matchup as a serious challenge as he continues his quest to become a legitimate world champion.

"Ask and I shall deliver," Jake said Wednesday. "August has more KO’s then me, more wins then me, more experience then me, but I like to gamble."

"The path to world champ starts here. Just straight up boxing."

26-year-old Paul is 7-1 with four KOs in his career ... but many have criticized him for taking on older MMA fighters with little to no boxing experience.

The one boxer he actually has on his record is Tommy Fury -- and that's his only loss.

35-year-old August is by far the smallest name Jake has ever agreed to fight ... but he's exactly the type of opponent the purists would want to see him face off against.

The 5'10", 200-lb. Houston native last fought in August, when he won via unanimous decision. His only loss came in 2018. According to his Instagram page, AA claims to be a Texas state champion.

August addressed the upcoming event in a statement ... saying, "I don't talk very much. I’m all about that action! Jake Paul has the money, the fame, the team and the resources but he doesn’t have my hunger."

"When that bell rings, I am going to go straight to Jake Paul and ring his bell and send him back to YouTube for good."

The bout is slated to go down December 15 at the Caribe Royale in Orlando.