**Preheat the Oven:** Preheat your oven to 425°F (220°C).
**Prepare the Ingredients:** Slice the chicken, bell peppers, and onion into thin strips.
**Make the Seasoning Mix:** In a small bowl, combine chili powder, cumin, smoked paprika, garlic powder, onion powder, salt, black pepper, and cayenne pepper.
**Coat the Ingredients:** In a large mixing bowl, toss the chicken, peppers, and onion with olive oil and the seasoning mix until evenly coated.
**Arrange on the Sheet Pan:** Spread the seasoned chicken and vegetables evenly on the sheet pan.
**Bake:** Roast in the preheated oven for 20-25 minutes, stirring halfway through, until the chicken is cooked through and the vegetables are tender.
**Add Lime Juice:** Remove the sheet pan from the oven and squeeze fresh lime juice over the fajita mixture.
**Serve:** Warm the tortillas and serve with your favorite toppings.