Craving sizzling fajita flavor but not in the mood to fire up the skillet? This Chicken Fajita Casserole has all the bold Tex-Mex taste of your favorite fajitas—baked into one irresistibly cheesy, oven-ready dish.

It’s quick to prep, packed with vibrant veggies, and delivers that smoky-spiced chicken goodness in every bite. Whether you’re serving it over rice, scooping it into warm tortillas, or simply digging in with a fork, this cozy casserole is about to earn a regular spot in your dinner rotation.

A Quick Word About the Fajita Seasoning

This recipe leans hard on a pantry MVP: fajita seasoning. Whether you’re using a pre-mixed blend or your own homemade version (think paprika, chili powder, cumin, garlic powder, onion powder, and a hit of cayenne), the seasoning does the heavy lifting here. It infuses the chicken and veggies with that warm, southwestern flavor we all know and love—no marinating time required.

Flavorful Ingredients That Bring It All Together

This casserole keeps things simple, but each ingredient plays a key role in delivering the full fajita experience.

Chicken Breasts: Boneless, skinless chicken breasts are sliced into strips for fast, even cooking. Want to switch it up? Chicken thighs work too—they’ll give a juicier, richer bite.
Bell Peppers: Red and yellow peppers add natural sweetness and vibrant color. You can use green peppers too for a more traditional fajita flavor with a slight bitterness.
Onion: Sliced white or yellow onion softens in the oven and brings savory depth to balance the sweetness of the peppers.
Fajita Seasoning: This is the magic ingredient. It turns ordinary chicken and vegetables into a Tex-Mex party.
Olive Oil: Helps the seasoning cling and the veggies roast to perfection.
Shredded Cheese: A melty blanket of cheddar—or a Mexican blend if you prefer—finishes the dish with creamy, salty goodness.

Optional, But Totally Worth It:

Tortillas: Serve with soft flour tortillas for a full-on fajita vibe.
Toppings: Think sour cream, diced avocado, fresh tomatoes, jalapeños, and cilantro. They add texture, temperature contrast, and fresh flavor.

Let’s Get Cooking: Step-by-Step

Season the Chicken First
In a large bowl, combine 1 tablespoon of olive oil with 1 tablespoon of fajita seasoning. Stir to create a thick paste. Add your chicken strips and toss them until fully coated. Using your hands here ensures every piece gets seasoned love.
Layer the Chicken
Place the seasoned chicken into a lightly greased 9×13-inch casserole dish, spreading it out in an even layer so it cooks uniformly.
Toss the Veggies
In the same bowl (no need to wash!), add the remaining olive oil and fajita seasoning. Toss in your sliced bell peppers and onion, mixing until everything’s nicely coated.
Build the Casserole
Spread the seasoned peppers and onions over the chicken in the dish. Then generously sprinkle the shredded cheese on top—this will melt into gooey perfection in the oven.
Bake It Up
Pop the casserole into a preheated 350°F oven and bake uncovered for 30 to 35 minutes. When it’s ready, the chicken should be cooked through (look for no pink in the center), the veggies tender, and the cheese bubbling and golden.
Garnish and Serve
Pull it from the oven and top with fresh cilantro for a hit of brightness. Serve hot with warmed tortillas and all your favorite toppings on the side. Taco night vibes = unlocked.

Want It Spicier or More Veggie-Loaded?

You can make this casserole your own in lots of easy ways:

Add sliced jalapeños into the veggie mix before baking for a spicier bite.
Throw in mushrooms, zucchini, or corn to up the veggie content.
Try Monterey Jack or Pepper Jack cheese for an extra kick of flavor.
Use a dairy-free cheese to make it completely lactose-free.

Storing, Reheating & Reinventing Leftovers

If you somehow don’t devour it all in one sitting, this casserole keeps beautifully.

Fridge: Store leftovers in an airtight container for up to 4 days.
Freezer: Yes, it freezes well! Let it cool completely, then wrap tightly or portion into freezer-safe containers. Reheat straight from frozen or thaw overnight and bake at 350°F until hot.
Reheat: Microwave individual portions or reheat in the oven covered with foil to keep it from drying out.

Leftover Magic: Turn extras into quesadillas, fajita wraps, or even toss over greens for a killer Tex-Mex salad.

Ready to bring fajita night to the oven? This Chicken Fajita Casserole delivers big-time flavor with a no-fuss method—and chances are, once you make it, you’ll be adding it to your “easy weeknight wins” list.