Preheat oven to 400°F and line a large sheet pan with parchment paper.
In a large bowl, mix olive oil, lime juice, chili powder, cumin, paprika, garlic powder, onion powder, salt, and pepper.
Add chicken, bell peppers, and onion to the bowl, tossing to coat evenly.
Spread the mixture in a single layer on the prepared sheet pan.
Bake for 20-25 minutes, flipping halfway through, until chicken is fully cooked.
Warm the tortillas in a dry skillet or microwave.
Serve fajitas in warm tortillas, topped with fresh cilantro, sour cream, avocado, and shredded cheese if desired.