If using wooden skewers, soak them in water for at least 20 minutes to prevent burning.
In a large bowl, combine olive oil, garlic powder, smoked paprika, onion powder, cumin, salt, black pepper, cayenne, and lemon juice. Stir well.
Add the chicken cubes to the marinade and toss until fully coated. Let sit for at least 10 minutes (or up to 24 hours in the fridge for deeper flavor).
Thread the chicken, bell peppers, and onion alternately onto the skewers.
Preheat your air fryer to 400°F for 3 minutes.
Place skewers in the air fryer basket in a single layer, working in batches if needed.
Cook for 12–14 minutes, flipping halfway through, until the chicken reaches an internal temperature of 165°F.
Let rest for 2 minutes before serving.