Peel the onions and slice them into 1/2-inch rounds. Gently separate them into individual rings.
Set up a dredging station with three shallow bowls: In the first, combine the flour, garlic powder, onion powder, cayenne pepper, salt, and pepper. In the second, whisk together the eggs. In the third, add the panko crumbs.
Preheat your air fryer to 350°F. Lightly coat the air fryer basket with cooking spray to prevent sticking.
Working in batches, dip each onion ring first into the flour mixture, coating all sides. Shake off any excess.
Next, dip it into the egg mixture, letting the excess drip off, then coat thoroughly with panko breadcrumbs. For extra-crispy rings, repeat the egg and panko steps a second time.
Arrange the coated rings in a single layer in the air fryer basket, making sure they don’t overlap. Lightly spray the tops with cooking spray.
Air-fry for 10–12 minutes, flipping halfway through, until golden brown and crisp.
Transfer cooked onion rings to a wire rack and repeat with the remaining batches.
Season with additional salt if desired and serve immediately with your favorite dipping sauce.