In a mixing bowl, combine the sweet chili sauce, soy sauce, sesame oil, garlic powder, ground ginger, and black pepper. Mix well to create the marinade.
Add the chicken thighs to the marinade, ensuring they are well coated. Let them marinate for at least 10 minutes for the best flavor.
Preheat your air fryer to 380°F (190°C).
Lightly coat the air fryer basket with cooking spray to prevent sticking.
Arrange the marinated chicken thighs in a single layer in the air fryer basket, skin side up.
Cook the chicken thighs in the air fryer for 20 minutes, flipping them halfway through the cooking time for even crispiness.
Check the internal temperature of the chicken; it should reach 165°F (74°C). If necessary, cook for an additional 2-3 minutes until fully cooked.
Once cooked, remove the chicken from the air fryer and let it rest for a few minutes before serving.
Garnish with sliced green onions and sesame seeds if desired.