In a medium mixing bowl, whisk together all-purpose flour, garlic powder, ground black pepper, and sea salt until evenly combined.

Preheat your air fryer to 350°F (175°C) for about 5 minutes.

Slice the banana peppers in half lengthwise and remove the seeds.

Dip each banana pepper slice into the flour mixture, making sure each piece is thoroughly coated. Let sit for about 5 minutes.

Arrange the coated banana pepper slices in a single layer in the air fryer basket and lightly spray both sides with olive oil spray.

Air fry the coated banana peppers at 350°F (175°C) for about 8 minutes.

Once golden brown, transfer the banana peppers to a paper towel-lined baking sheet and allow to cool for about 5 minutes.