In a bowl, combine the sliced chicken, bell peppers, onion, olive oil, fajita seasoning, salt, and pepper. Mix well to coat the chicken and vegetables evenly.
Place the mixture in the air fryer basket in a single layer.
Cook for 10-12 minutes, shaking the basket halfway through, until the chicken is cooked through and the vegetables are tender.
Warm the flour tortillas in the air fryer for 1-2 minutes.
Serve the chicken and vegetables in the tortillas, and enjoy!