Preheat Oven: Preheat the oven to 350°F (175°C). Grease a loaf pan or line it with parchment paper.
Combine Dry Ingredients: In a large bowl, combine the all-purpose flour, baking powder, baking soda, salt, and cinnamon.
Combine Wet Ingredients: In another bowl, beat the eggs. Add the vegetable oil, granulated sugar, and vanilla extract. Mix well.
Mix Together: Pour the wet mixture into the bowl with the dry ingredients and gently mix until well combined. Do not overmix.
Fold in Zucchini and Walnuts: Fold in the grated zucchini and chopped walnuts until evenly distributed.
Transfer and Bake: Transfer the batter to the prepared loaf pan. Bake in the preheated oven for 50-60 minutes, or until a toothpick inserted into the center of the bread comes out clean.
Cool the Bread: Remove the bread from the oven and let it cool in the pan for 10 minutes. Then, remove the bread from the pan and let it cool completely on a wire rack.