Preheat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or grease the cups.
In a medium bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking soda, baking powder, and salt until well combined.
In a large bowl, beat the granulated sugar, light brown sugar, and eggs together until smooth and creamy.
Add the vegetable oil and vanilla extract to the egg mixture and mix until fully incorporated.
Stir the dry ingredients into the wet ingredients until just combined; do not overmix.
Fold in the grated zucchini and mini chocolate chips gently until evenly distributed.
Divide the batter evenly among the prepared muffin cups, filling each about 3/4 full.
Bake for 18 to 20 minutes or until a toothpick inserted into the center of a muffin comes out clean.
Remove the muffins from the oven and allow them to cool in the pan for 5 minutes.
Transfer the muffins to a wire rack to cool completely before serving.