Preheat oven to 350 degrees F (175 degrees C). Line a baking sheet with aluminum foil; mist with cooking spray.
Mix onion powder, garlic powder, seasoned salt, and pepper together in a bowl.
Sprinkle onion powder mixture over both sides of the chicken thighs. Lift up the skin to create a pocket; stuff pocket with 2 tablespoons of pesto and 1 tablespoon of mozzarella cheese. Wrap chicken with 2 slices of bacon, using bacon to seal the pocket. Place chicken thighs seam-side down on the baking sheet.
Bake in the preheated oven until an instant-read thermometer inserted into the chicken, near the bone, reads at least 165 degrees F (74 degrees C), about 1 hour.