Yes, you can use frozen Brussels sprouts for air fryer cooking. Thaw the frozen sprouts first by placing them in the refrigerator or using the defrost function on your microwave. Make sure to pat them dry to remove excess moisture before air frying. Remember that frozen Brussels sprouts might take longer to cook than fresh ones, so adjust the cooking time as needed. While they might not be as crispy as fresh sprouts, proper thawing and drying can help achieve the right texture.