Slice the bananas into thin slices, about 1/4 inch thick.
Place the banana slices in a bowl and cover with olive oil. Mix until combined.
Place the banana slices in a single layer in the air fryer. Work in batches if need be.
Sprinkle the banana slices with kosher salt.
Air fry for 8-10 minutes at 350F, flipping halfway through, until bananas are lightly browned and crispy.
Remove from the air fryer and let cool on a baking sheet or cooling rack. Repeat with remaining bananas.
Video
Notes
You want to choose bananas that are just barely ripened. If they are too ripe, they will be difficult to cut into even slices. If you prefer, you can also use unripe, green bananas.
The trick to getting crispy banana chips is to slice the bananas very thin. It also helps if they are very uniformly cut. If they are the same size you won't have to worry about the bananas cooking in different amounts of time.
Pro Tip: This recipe can be made in the air fryer unit with a basket or the air fryer oven. If you are using the air fryer oven, use the middle rack and select the "Air Fry" function.
Pro Tip: Check your food as it cooks. Each air fryer runs a bit differently. Sometimes airfying is a trial and error process. Check your food as it cooks to learn your air fryer better! When cooking a new recipe or food items be sure to check your food often to help avoid over/under cooking.