Preheat the air fryer to 390°F (200°C).
Place the chicken strips in a large bowl and drizzle with vegetable oil.
Sprinkle the fajita seasoning over the chicken and toss until evenly coated.
Add the sliced bell peppers and onion to the bowl and mix well so the vegetables are coated with the seasoning.
Transfer the chicken and vegetables into the air fryer basket in an even layer.
Cook for about 15 minutes, shaking or tossing halfway through cooking.
Once the chicken is fully cooked and the vegetables are slightly charred, remove from the air fryer. This step finishes the delicious air fryer chicken fajitas.
Serve with warm tortillas, pico de gallo, avocado slices, or guacamole.