Preheat your air fryer to 375°F (190°C).
Generously grease a donut pan with butter or cooking spray and set aside.
Open the can of biscuits and use a small round cookie cutter to cut a hole in the center of each biscuit, creating a donut shape.
Save the donut holes and cook them alongside the donuts if desired.
Place each biscuit round into the prepared donut pan, gently pressing them into the mold.
Air fry for 4 minutes.
Carefully flip each donut and continue cooking for another 4 minutes, or until golden brown and fully cooked.
Remove the Easy Air Fryer Donuts from the air fryer.
Dip each warm donut into the melted butter.
Combine the sugar and cinnamon in a shallow bowl.
Roll the butter-coated donuts in the cinnamon sugar mixture until completely covered.
Serve immediately while warm and enjoy.