Preheat the air fryer to 400°F and lightly grease the air basket with oil (optional).
Place the frozen fries into an air fryer. Cook for 7 minutes then shake the basket or stir the fries. Continue cooking and shaking the basket every 3 minutes twice. If the fries are not ready, continue cooking, keep shaking, and checking the fries very 1-1½ minutes until they are fully cooked and crispy.
Air frying times may vary depending on the thickness of the fries. Be sure to check for doneness at 10 minutes.