Preheat the air fryer to 400°F. Line the air fryer basket and its walls with aluminum foil. Add the popcorn kernels and oil into the basket, and use a spoon to toss gently. Then spread out the kernels as much as possible in a single layer so they are not touching each other.

Air fry for 5 minutes and remove from the air fryer. If you notice any unpopped kernels, return them to the air fryer for 3 more minutes.

Season the popcorn with salt immediately and add any other toppings like melted butter or popcorn flavorings as desired.