Preheat the air fryer to 400°F (200°C) for 3–5 minutes while you prepare the coating.
Season the cod fillets on both sides with salt, pepper, and lemon juice, then set aside for a few minutes.
In one shallow bowl, whisk the egg until smooth; in a second bowl, combine the parmesan, panko breadcrumbs, garlic powder, paprika, and dried parsley.
Dip each seasoned cod fillet into the egg, letting excess drip off, then press it firmly into the parmesan breadcrumb mixture until completely coated.
Lightly mist the air fryer basket with cooking spray, arrange the coated cod fillets in a single layer with space between them, and spray the tops with a bit more oil.
Cook at 400°F (200°C) for 10–12 minutes, flipping gently halfway, until the crust is golden and the fish flakes easily with a fork.
Serve the crispy air fryer parmesan crusted cod immediately with lemon wedges, fresh parsley, and your favorite side dishes.