In a mixing bowl, combine 2 cups fresh blueberries, 1/2 cup granulated sugar, 1 teaspoon lemon zest, and 1 tablespoon lemon juice. Mix until blueberries are well-coated. Set aside for 10 minutes.
In another bowl, whisk together the 3/4 cup all-purpose flour, 1/4 cup brown sugar, 1 teaspoon baking powder, and 1/2 teaspoon salt. Add 3/4 cup whole milk melted 4 tablespoons unsalted butter, and 1 teaspoon vanilla extract. Stir until smooth.
Pour the blueberry mixture into a greased air fryer-safe pan or dish.
Gently pour the batter over the blueberries, spreading evenly.
Insert the pan into the air fryer. Set air fryer temperature to 320 degrees F (160°C) and set cook time for 15-20 minutes or until the top is golden brown and a toothpick comes out clean when inserted into the center of the cobbler.
Let it cool for a few minutes before serving