In a small bowl, combine the paprika, garlic powder, salt, and black pepper; mix and set aside.
Spray the slow cooker insert with cooking spray and trim any excess fat from the chicken thighs on a cutting board.
Divide the seasoning mixture in half. Sprinkle half over the tops of the chicken thighs, rub briefly, flip them, then sprinkle the remaining seasoning and rub again.
Roll each thigh as it naturally rolls and place the thighs seam-side down in the bottom of the slow cooker in a single layer.
Pour the BBQ sauce evenly over the chicken thighs, cover, and cook on low for 4 to 5 hours (about 240–300 minutes) until cooked through.
When done, preheat the oven broiler. Line a sheet pan with foil and lightly spray with cooking oil.
Transfer the thighs to the prepared sheet pan, leaving space between pieces. Brush extra BBQ sauce over each thigh.
Broil 1 to 3 minutes to crisp the edges, watching closely to avoid burning, then remove and serve.
