Preheat the air fryer. Set your air fryer to 390–400°F (200°C). Preheating helps the broccoli start crisping right away.
Prep the broccoli. Wash and thoroughly dry the florets. Cut them into uniform, bite-size pieces so they cook evenly.
Trim the stems and slice them thin—don’t toss them out.
Season well. In a large bowl, toss the broccoli with oil, salt, pepper, garlic powder, and red pepper flakes if using. Every piece should have a light, even coat of oil.
Load the basket in a single layer. Add the broccoli to the air fryer basket without crowding. If your air fryer is small, cook in two batches for best results.
Air fry for 6–8 minutes. Shake the basket halfway through to promote even browning.
Start checking at 6 minutes; florets should have crisp tips and tender stems.
Finish and serve. Toss the hot broccoli with lemon juice or zest and sprinkle with Parmesan if you like. Taste and adjust salt and pepper. Serve immediately for peak crispiness.