Previously prosecutors had tried to have him face adult charges for the murder of Kenzie Houk, when he was just 11-year-old.
Using his own shotgun, designed for kids, he is accused of shooting her and then walking her eight-year-old daughter to school.
Now a three-judge panel has reversed that ruling, which means if convicted Brown, now 13, will be freed by the age of 21 instead of facing life imprisonment like an adult would.
A Lawrence County judge based his decision to try Brown as an adult largely on the boy's refusal to take responsibility for the crime, which both defense and prosecution psychologists testified is necessary for rehabilitation through the juvenile court system.
But Friday Superior Court judges Judith Olson and Cheryl Lynn Allen said that decision violated Brown's Fifth Amendment right against self-incrimination.
It remains to be seen whether prosecutor's will appeal this decision.