Place the chicken thighs into the slow cooker, adding the minced garlic, Kosher salt, and black pepper.
Toss the ingredients together to coat the chicken, then arrange the pieces with the skin side facing up.
Evenly sprinkle the packed brown sugar over the chicken.
Cover and cook on a low setting for 8 hours or choose the high setting for 4 hours, until the chicken is tender and fully cooked.