Take your bell peppers and remove the tops. Cut out the center part and remove seeds of bell peppers. Cut each bell pepper into thin strips and place into a medium bowl.
Cut the onion and chicken into thin strips. Add to the bowl.
Mix cumin, chili powder, garlic powder, salt, and pepper together in a small bowl. Stir to combine.
Add the olive oil to the chicken, pepper, and onion strips. Mix until oil coats everything. Add the fajita seasoning to the bowl and mix together with a spoon or your hands until seasoning coats chicken, peppers, and onion.
Place the uncooked fajitas in the basket of your air fryer. Make sure mixture is spread out.
Cook in your air fryer for 15 minutes at 390 degrees F, tossing every 4-5 minutes and checking for doneness around 12 minutes. Cook until vegetables are charred and chicken is cooked through. (This may take up to 20 minutes, depending on your air fryer and how charred you want your veggies).
Notes
When slicing your chicken breast, slice it into thin strips, similar to how you slice the onion and pepper. You can see in my photos, my chicken is a similar size to the onion and pepper slices.
Different air fryers cook differently. Start checking for doneness around 12 minutes, and cook for longer if needed. You may need up to 20 minutes.
Really make sure you've tossed all your veggies and chicken in the oil and then distributed the seasoning throughout the bowl when mixing. This will make sure everything is perfectly seasoned.
I used 2 bell peppers (orange and red), when I made this dish, but you can actually use more if you want. And it doesn't matter which colors you use! Yellow, green, orange, red? Use what you love (and have on hand!)