If you're searching for the ultimate comfort food with a Tex-Mex twist, this Cheesy Chicken Fajita Casserole is absolutely dreamy! Imagine tender strips of chicken, vibrant sautéed peppers and onions, all smothered in melty cheese and baked till bubbly. Each forkful delivers a fiesta of flavors with just the right amount of spice.

What makes this casserole the very best? It's incredibly simple-everything comes together in one dish, and you can have it prepped and ready in under an hour. No need to fuss with tortillas or stovetop juggling; the oven does all the work!

This is my ultimate go-to when I need a hearty family dinner or want something irresistibly cheesy for a potluck. Trust me, it's one of those recipes that gets devoured before you can say "seconds." Bring it to your next gathering, and watch it disappear!

Cheesy Chicken Fajita Casserole in a casserole dish, topped with melted cheese and colorful bell peppers

Why You'll Love This Recipe

Comforting and satisfying - Packed with gooey cheese and vibrant fajita flavor.
Super easy to prep - Minimal chopping and everything bakes together in one dish.
Family-friendly and customizable - Mild enough for kids, but easy to spice up for heat-lovers.
Great for meal prep - Tastes just as delicious reheated the next day.

Key Ingredients for Cheesy Chicken Fajita Casserole

See recipe card below for full list of measurements, ingredients, and instructions.

Chicken Breast

Chicken breast is the star of this casserole, providing lean, juicy protein that soaks up all those bold fajita flavors. Cut the chicken into thin strips for fast, even cooking. If you prefer, boneless, skinless chicken thighs will deliver even more flavor and extra tenderness.

Bell Peppers

Classic fajita bell peppers add sweetness, color, and vibrance. Use a mix of red, yellow, and green peppers for a gorgeous, eye-catching dish. Slice them into thin strips for that signature fajita look. Feel free to sub in poblano peppers for a little more earthiness, or use whatever color you have on hand.

Onion

Sliced onions bring softness, a subtle bite, and intense savory flavor as they roast. Yellow onions are ideal, but white or red onions will work too. Slice thinly so they nearly melt into the cheesy layers.

Fajita Seasoning

This essential spice blend infuses the dish with smoky, zesty flavor and a hint of heat. Use a store-bought packet for convenience, or mix up your own with chili powder, cumin, paprika, and garlic powder. Want a little more kick? Add a pinch of cayenne.

Shredded Cheese

A mix of cheddar and Monterey Jack makes every bite ooey-gooey and irresistible. Pre-shredded cheese is fine for ease, but freshly grated cheese will melt smoother. You can use all cheddar, Colby Jack, or even pepper Jack if you like more spice.

Cheesy Chicken Fajita Casserole cooking process

Instructions for Cheesy Chicken Fajita Casserole

See recipe card below for full list of measurements, ingredients, and instructions.

Prep the Oven and Your Pan

Start by preheating your oven to 375°F (190°C). Lightly grease a 9x13-inch casserole dish with cooking spray or a drizzle of olive oil to prevent sticking.

Cook the Chicken and Veggies

In a large skillet, heat olive oil over medium-high heat. Add the chicken strips, sprinkle with fajita seasoning, garlic powder, salt, and pepper, and sauté for 4-5 minutes until just starting to brown (the chicken does not need to be fully cooked yet). Add the sliced bell peppers and onion, and cook for another 3-4 minutes, stirring often, until everything is slightly softened.

Assemble the Casserole

Spread the cooked rice evenly on the bottom of your prepared casserole dish. Top with the sautéed chicken, peppers, and onions. Sprinkle the drained diced tomatoes evenly over the top.

In a small bowl, whisk together the sour cream and half of the cheddar cheese. Dollop this mixture over the casserole, then gently spread it out. Sprinkle the Monterey Jack cheese and remaining cheddar cheese evenly over the top.

Bake Until Bubbly

Place the casserole in the oven and bake uncovered for 20-25 minutes, or until the cheese is melted, bubbly, and slightly golden around the edges.

Finish and Serve

Let the casserole rest for 5 minutes before serving. Garnish with chopped fresh cilantro if desired. Serve hot and enjoy the cheesy goodness!

Recipe Variations

Make It Gluten-Free

This casserole is naturally gluten-free if you ensure your fajita seasoning is certified gluten-free. Double-check any store-bought spice blends for hidden wheat or gluten-containing fillers.

Spice It Up

Like it with extra heat? Swap some or all of the bell peppers for poblano or jalapeño peppers. Add a pinch of crushed red pepper or use pepper Jack cheese for a spicy kick.

Veggie-Loaded Option

Add black beans, corn kernels, or zucchini slices to sneak in more veggies and fiber. These blend beautifully with the Tex-Mex flavors and create an even heartier casserole.

Low-Carb Swap

Replace the rice with cauliflower rice for a lower-carb, lighter version-you'll hardly miss the grains once it's loaded with all that cheesy flavor!

Rotisserie Chicken Shortcut

Short on time? Use shredded rotisserie chicken instead of sautéing your own. Toss it with the spices and veggies, then follow the rest of the recipe as written.

Serving Suggestions

Turn this cozy casserole into a complete meal by serving it with a crisp green salad dressed with lime vinaigrette or a simple side of black beans. A dollop of extra sour cream, sliced avocado, and a sprinkle of fresh cilantro make tasty garnishes. Scoop it up with tortilla chips for a fun twist, or add a side of warm flour tortillas for the ultimate Tex-Mex feast.

Storage and Reheating

Store leftovers tightly covered in the refrigerator for up to 4 days. To reheat, cover with foil and warm in a 350°F oven for 15-20 minutes, or microwave individual servings until heated through. This casserole also freezes well-wrap tightly in plastic and foil and freeze for up to 2 months. Thaw overnight in the fridge before reheating.

Frequently Asked Questions About Cheesy Chicken Fajita Casserole (FAQ)

Q: Can I make Cheesy Chicken Fajita Casserole ahead of time?

A: Absolutely! Assemble the casserole up to a day in advance, cover, and refrigerate. Bake as directed when ready to serve, adding a few extra minutes if baking straight from the fridge.

Q: What kind of cheese works best for this casserole?

A: A combination of cheddar and Monterey Jack gives the perfect gooey melt and sharp flavor, but you can use any good melting cheese such as Colby Jack or even pepper Jack for more heat.

Q: Can I use cooked chicken or rotisserie chicken?

A: Yes! Shredded, pre-cooked or rotisserie chicken works great-just toss with the seasoning and veggies before layering the casserole.

There's so much to love about this Cheesy Chicken Fajita Casserole-crowd-pleasing flavor, easy prep, and pure comfort in every bite. I hope you enjoy making it as much as I do! If you try this recipe, be sure to leave a comment or rating to let me know how it turned out for you. Happy cooking!