Preheat your oven to 425°F and lightly grease a large baking sheet or line it with parchment paper for easier cleanup.
Slice the bell peppers, onion, and chicken into thin strips so they cook evenly.
Place the chicken, peppers, and onion in a large bowl. Drizzle with olive oil.
In a small bowl, combine the seasonings, then sprinkle them over the chicken and vegetables. Squeeze the lime juice over the top. Wearing disposable food-safe gloves, toss everything together until the chicken and veggies are evenly coated.
Using tongs, spread the chicken and vegetables across the prepared baking sheet in a single layer. Avoid overcrowding the pan so the ingredients roast properly.
Bake for 25 to 30 minutes, stirring halfway through if desired, until the chicken is fully cooked and the vegetables are tender.
Remove from the oven and sprinkle with fresh cilantro. Serve in warm flour tortillas with your favorite fajita toppings such as sour cream, shredded cheese, guacamole, or salsa.