In a medium bowl, whisk together 1 cup yellow cornmeal, 1 cup all-purpose flour, 1 3/4 teaspoons baking powder, 2 tablespoons sugar, 3/4 teaspoon salt, and 1 1/4 teaspoons garlic powder.
In a separate bowl, beat 1 large egg. Add 6 tablespoons low-fat buttermilk and 3 tablespoons melted unsalted butter and mix until combined. Stir in 3 tablespoons grated yellow onion and 2 tablespoons chopped green onion.
Pour the wet mixture into the dry ingredients and stir gently until just combined (batter will be slightly lumpy). Do not overmix. Let the batter rest 5 minutes.
Preheat the air fryer to 380°F for 5 minutes. Lightly spray the air fryer basket with nonstick cooking spray.
Using a tablespoon, scoop tablespoonfuls of batter into the basket, spacing them so they do not touch. Work in batches if needed.
Cook at 380°F for 4–5 minutes. Carefully flip each hush puppy and cook an additional 3–5 minutes, or until golden and crispy.
Remove cooked hush puppies to a plate and repeat with remaining batter. Serve warm.