Preheat the air fryer to 375°F (190°C) for about 5 minutes.
- In a large bowl, combine ground beef, breadcrumbs, Parmesan cheese, egg, milk, minced garlic, Italian seasoning, salt, and pepper. Mix until just combined; avoid overmixing to keep meatballs tender.
- Wet your hands and roll the mixture into 1½-inch meatballs. You should get approximately 24 meatballs.
- Lightly spray the air fryer basket with cooking spray. Place meatballs in a single layer, ensuring they aren’t touching. Cook in batches if necessary.
- Cook at 375°F (190°C) for 10–12 minutes, flipping halfway through, until the internal temperature reaches 165°F (74°C).
- Let the meatballs rest for 3–5 minutes before serving.