Gather the ingredients. Preheat the oven to 350 degrees F (175 degrees C). Spray a 9x13-inch pan with cooking spray.
Mix pineapple with juice and cake mix together in a large bowl until well combined; pour batter into the prepared pan.
Bake in the preheated oven until golden brown, about 25 minutes. Let cake cool; serve with whipped topping.
