Preheat Your Oven. Preheat the oven to 375°F and line a muffin tin with paper liners or grease the cups.
Mix Dry Ingredients. In a large bowl, whisk together the flour, sugar, baking powder, and salt until well combined.
Prepare Wet Ingredients. In a separate bowl, melt the butter and let it cool slightly. Then, whisk in the eggs, lemon zest, lemon juice, and milk until smooth.
Combine Wet and Dry Ingredients. Pour the wet ingredients into the dry ingredients and gently fold them together until just combined. Be careful not to overmix.
Add Blueberries. Gently fold the blueberries into the batter, being careful not to crush them.
Fill Muffin Cups. Divide the batter evenly among the prepared muffin cups, filling each cup about two-thirds full.
Bake. Bake the muffins in the preheated oven for 18-20 minutes, or until the tops are golden brown and a toothpick inserted into the center comes out clean.
Cool and Enjoy. Allow the muffins to cool in the pan for a few minutes before transferring them to a wire rack to cool completely. Serve warm or at room temperature.