Preheat the Oven: Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.
Prepare the Batter: In a large mixing bowl, combine the lemon cake mix, instant lemon pudding mix, eggs, vegetable oil, water, lemon juice, and lemon zest. Beat with an electric mixer or whisk until smooth and well combined.
Bake the Cake: Pour the batter into the prepared dish and spread it evenly. Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean.
Cool the Cake: Remove the cake from the oven and let it cool in the pan on a cooling rack.
Make the Glaze: In a bowl, whisk together powdered sugar and lemon juice until smooth. Adjust the consistency by adding more sugar for a thicker glaze or more juice for a thinner glaze.
Glaze the Cake: Pour the glaze over the cooled cake, spreading it evenly with a spoon or spatula. Sprinkle with lemon zest for extra flavor and decoration.
Serve and Enjoy: Slice into squares and serve.