Gather all ingredients. Preheat the oven to 350 degrees F (175 degrees C). Grease and flour a 9x13-inch baking pan.
Stir lemon gelatin into the boiling water in a large bowl; let cool to room temperature, 30 minutes.
Once gelatin has cooled, beat in cake mix, eggs, and vegetable oil with an electric mixer on medium speed for 2 minutes.
Spread batter evenly in the prepared baking pan.
Bake until a toothpick inserted into the center of the cake comes out clean, 30 to 35 minutes.
Meanwhile, whisk together powdered sugar and lemon juice in a small bowl.
Remove cake from oven and place on a wire rack. Using a chopstick or straw, poke holes about 1-inch apart all over the cake. Drizzle glaze over the cake and spread evenly. Let cake cool completely on wire rack, about 1 hour.
