Preheat the oven to 425°F (220°C).
In a medium saucepan, combine the rice and water. Bring to a boil over high heat, then reduce heat to low, cover, and simmer for 15 minutes or until the rice is tender and water is absorbed. Remove from heat and let stand covered for 5 minutes.
In a small bowl, mix together chili powder, ground cumin, smoked paprika, garlic powder, onion powder, dried oregano, cayenne pepper, salt, and black pepper to make the fajita seasoning.
Place the sliced chicken, red bell pepper, yellow bell pepper, green bell pepper, and onion on a large sheet pan.
Drizzle the olive oil over the chicken and vegetables, then sprinkle the fajita seasoning evenly on top.
Toss everything together on the sheet pan to coat the chicken and vegetables evenly with oil and seasoning.
Spread the chicken and vegetables out in an even layer on the sheet pan.
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.
Fluff the cooked rice with a fork and divide it among four bowls.
Top each bowl of rice with the roasted chicken and vegetables.
Garnish with chopped fresh cilantro and lime wedges for squeezing over the top before serving.