Preheat the air fryer to 380º F.
Give the green beans a good rinse under cool water; trim the ends off.
Place the green beans into a large mixing bowl and gently pat them dry with paper towels. Drizzle them with olive oil, then add the garlic powder, sea salt, and cracked black pepper. Toss the green beans thoroughly to make sure they are evenly coated. I typically just use my bare hands to make sure all of the beans are nicely coated.
Transfer the green beans to the air fryer basket once it's heated and cook for 8 minutes, shaking the basket halfway through.
Pop the green beans onto a serving platter, squeeze the fresh lemon juice over the beans, and top them with freshly grated parmesan and lemon zest.