Preheat the Oven: Preheat your oven to 350°F. This gives the oven plenty of time to reach the proper temperature while you prepare the batter.
Prepare the Loaf Pans: Lightly coat two 8×4-inch loaf pans with nonstick cooking spray. This helps the banana bread release easily after baking and makes cleanup much simpler.
Combine the Ingredients: Add the yellow cake mix, eggs, vegetable oil, and ripe bananas to a large mixing bowl. There's no need to mash the bananas beforehand—just break each banana into a few large pieces and add them directly to the bowl.
Mix the Batter: Using an electric mixer, beat everything together on medium speed for about 1 minute. The bananas will break down as you mix, creating a smooth, well-combined batter.
Fill the Pans: Divide the batter evenly between the prepared loaf pans. Use a spatula to spread the batter into an even layer so the loaves bake uniformly.
Bake Until Golden: Place the pans in the oven and bake for 40 to 45 minutes, or until a toothpick or butter knife inserted into the center comes out clean. The tops should be lightly golden and spring back when gently touched.
Cool Before Slicing: Let the loaves cool in the pans for about 15 minutes. Then carefully remove them from the pans and transfer them to a wire rack to cool completely. Once cooled, slice and enjoy your homemade banana bread.