Preheat the oven to 425°F (220°C).
In a large bowl, combine the chili powder, ground cumin, smoked paprika, garlic powder, onion powder, cayenne pepper, salt, and black pepper.
Add the sliced chicken breasts to the bowl and toss to coat evenly with the spice mixture.
Add the sliced red, yellow, and green bell peppers and the sliced onion to the bowl with the chicken. Drizzle the olive oil over the mixture and toss everything together until well coated.
Spread the chicken and vegetable mixture evenly on a large sheet pan in a single layer.
Bake in the preheated oven for 20-25 minutes, stirring halfway through, until the chicken is cooked through and the vegetables are tender.
While the chicken and vegetables are baking, warm the cooked white rice if needed.
To assemble the rice bowls, divide the cooked rice evenly among four bowls.
Top each bowl of rice with the sheet pan chicken fajita mixture.
Garnish with chopped fresh cilantro and serve with lime wedges on the side for squeezing over the bowls.