Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the shredded chicken, broccoli florets, and cooked rice.
In a separate bowl, whisk together the cream of mushroom soup, milk, garlic powder, onion powder, salt, and pepper until well blended.
Pour the soup mixture over the chicken, broccoli, and rice, stirring gently to combine.
Transfer the mixture to a greased baking dish and spread evenly.
Sprinkle shredded cheddar cheese on top of the casserole.
Bake in the preheated oven for 25-30 minutes or until cheese is bubbly and golden brown.
Let it cool for a few minutes before slicing and serving.