"King of Freestyle" Stevie B: I'm Changing My Deadbeat Ways

Latin legend Stevie B just pled guilty to owing $420,000 in unpaid child support -- but he has promised the court ... he's gonna do his damnedest to pay it off.

Stevie -- real name Steven Bernard Hill -- was arrested outside his concert in Massachusetts this weekend for owing the enormous sum to his baby mama.

Stevie was arraigned in court this morning -- and according to court sources, he promised to pay $921.25 a week in child support, and an additional $500 a month toward his arrears.

Stevie B is still in custody -- and must pay a $10,000 lump sum toward the $420,000 balance in order to get out of jail.