Preheat an air fryer to 350 degrees F (175 degrees C).
Slice polenta into long, thin slices resembling french fries.
Spray the bottom of the basket with cooking spray. Place 1/2 of the polenta fries in the basket and lightly mist the tops with cooking spray. Season with salt and pepper.
Cook in the preheated air fryer for 10 minutes. Flip the fries with a spatula and cook until crispy, about 5 minutes longer. Transfer fries to a paper towel-lined plate. Repeat with remaining half of fries.