Slice each sweet potato into 1/4-inch thick rounds using a sharp knife or mandoline slicer.
Preheat the air fryer to 130°F (54°C) or the lowest temperature setting available.
Place the sweet potato slices in a single layer inside the air fryer basket. Avoid overlapping to ensure even drying.
Air fry the sweet potato slices at 130°F (54°C) for 2 hours, flipping the slices halfway through the cooking time.
Check the texture after 2 hours; the treats should be dried but still slightly flexible. If needed, continue drying in 15-minute increments until desired chewiness is reached.
Remove the dried sweet potato treats from the air fryer and let them cool completely on a wire rack.
Store the cooled treats in an airtight container at room temperature for up to 2 weeks.