Preheat your air fryer to 300°F (150°C) for 5 minutes.
Peel the bananas and slice them into 1/8-inch-thick rounds.
In a small bowl, mix the sugar and ground cinnamon until well combined.
Gently toss the banana slices with the melted coconut oil or butter until lightly coated.
Sprinkle the cinnamon-sugar mixture over the banana slices and toss gently for even coverage.
Arrange the slices in a single layer in the air fryer basket without overlapping. Cook in batches if needed.
Air fry the Cinnamon Sugar Air Fryer Banana Chips for 15 minutes, flipping halfway through. Watch closely near the end so they do not burn.
Remove the banana chips when golden and crisp around the edges, then transfer them to a wire rack to cool completely. They will crisp up more as they cool.