Yes, you can cook frozen foods in an air fryer. Air fryers are designed to cook food quickly and evenly by circulating hot air around the ingredients. Frozen foods like french fries, chicken nuggets, mozzarella sticks, and even vegetables can be cooked in an air fryer without the need for defrosting. The cooking time may be slightly longer compared to fresh or thawed food, but the end result is usually crispy and delicious. It is important to follow the specific instructions for each food item and adjust the cooking time and temperature accordingly.