Pat the chicken thighs dry with paper towels. Removing excess moisture is the most important step for achieving maximum crispiness. Place the dried chicken in a large mixing bowl and drizzle with olive oil, tossing to coat evenly.
In a small bowl, whisk together the grated parmesan cheese, garlic powder, onion powder, dried parsley, paprika, salt, and black pepper. Ensure the parmesan is finely grated so it sticks well to the chicken skin.
Sprinkle the seasoning mixture over the chicken thighs. Use your hands or tongs to press the coating onto the skin and the underside of the meat. Make sure every nook and cranny is covered with the garlic parmesan mixture.
Preheat your air fryer to 380°F (195°C). Place the chicken thighs in the air fryer basket in a single layer, skin-side down. Do not overcrowd the basket. Cook for 12 minutes.
Flip the chicken thighs so they are skin-side up. Continue cooking for another 8 to 10 minutes, or until the skin is golden brown and crispy and the internal temperature reaches 165°F (74°C). Let the chicken rest for 5 minutes before serving.