Preheat the air fryer to 400°F (200°C).
In a mixing bowl, whisk together the flour, water, garlic powder, onion powder, smoked paprika, salt, and black pepper until smooth.
Add the cauliflower florets to the batter and toss until well-coated.
Lightly spray the air fryer basket with cooking spray to prevent sticking.
Place the battered cauliflower florets in a single layer in the air fryer basket. You may need to cook in batches.
Air fry the cauliflower for 10-12 minutes, shaking the basket halfway through for even cooking, until the cauliflower is crispy and golden brown.
In a separate bowl, combine the buffalo hot sauce and melted butter. Toss the cooked cauliflower in the buffalo sauce mixture until well-coated.
Return the coated cauliflower to the air fryer and cook for an additional 2-3 minutes to help set the sauce.
Serve hot, garnished with chopped fresh parsley if desired.