Preheat your oven to 400°F (200°C).
In a large mixing bowl, combine the sliced chicken, red and yellow bell peppers, and onion.
Drizzle the olive oil over the chicken and vegetables.
Add the chili powder, cumin, garlic powder, smoked paprika, salt, and black pepper to the bowl. Toss everything together until the chicken and vegetables are evenly coated.
Spread the chicken and vegetable mixture evenly onto the sheet pan in a single layer.
Bake in the preheated oven for 20-25 minutes, or until the chicken is cooked through and the vegetables are tender, stirring halfway through the cooking time.
Remove the pan from the oven and squeeze fresh lime juice over the chicken and fajitas for added flavor.
Serve warm, garnished with fresh cilantro if desired, along with tortillas or over rice.