Preheat the oven to 350°F (175°C) and grease a 9x13-inch baking dish.
In a large mixing bowl, combine cooked chicken, uncooked rice, chicken broth, cream of chicken soup, frozen vegetables, garlic powder, onion powder, salt, and pepper. Stir until well combined.
Pour the mixture evenly into the prepared baking dish.
Cover with aluminum foil and bake for 45 minutes.
Remove foil, sprinkle shredded cheese on top, and bake for another 15 minutes or until the cheese is melted and bubbly.
Let the casserole rest for 5–10 minutes before serving to allow the sauce to set.