Slice the bananas into thin rounds, about 1/8 inch thick.
In a bowl, toss the banana slices with lemon juice to prevent browning.
In a separate small bowl, mix together the sugar and cinnamon.
Spray the air fryer basket with cooking spray to prevent sticking.
Arrange the banana slices in a single layer in the air fryer basket, making sure they do not overlap.
Sprinkle the cinnamon sugar mixture evenly over the banana slices.
Air fry at 350°F for 10-15 minutes, shaking the basket halfway through to ensure even cooking.
Check for crispness; if they are not crispy enough, air fry for an additional 2-3 minutes.
Once done, remove the banana chips from the air fryer and let them cool completely before serving.