Preheat the oven to 425°F (220°C).
In a large bowl, combine the olive oil, chili powder, ground cumin, smoked paprika, garlic powder, onion powder, crushed red pepper flakes, salt, and black pepper. Stir to create the fajita seasoning mixture.
Add the thinly sliced chicken breasts, red bell pepper, yellow bell pepper, green bell pepper, and red onion to the bowl with the seasoning mixture. Toss everything together until the chicken and vegetables are evenly coated.
Spread the chicken and vegetable mixture evenly on a large rimmed sheet pan in a single layer.
Roast in the preheated oven for 20 to 25 minutes, stirring halfway through, until the chicken is cooked through and the vegetables are tender and slightly charred.
While the chicken and vegetables are roasting, prepare the cooked white rice according to package instructions if not already cooked.
To assemble the rice bowls, divide the cooked rice evenly among four bowls.
Top each bowl of rice with an equal portion of the roasted chicken and fajita vegetables.
Garnish each bowl with chopped fresh cilantro and serve with lime wedges on the side for squeezing over the top.
Serve immediately and enjoy your sheet pan chicken fajitas rice bowls.