Gather the ingredients. Preheat the oven to 350 degrees F (175 degrees C).
Combine cooked macaroni, tuna, and condensed soup together in a 9x13-inch baking dish; sprinkle with cheese.
Bake in the preheated oven until bubbly, about 25 minutes. Sprinkle with fried onions; bake 5 minutes more.
