Preheat an air fryer to 390 degrees F (195 degrees C).

Sift flour, baking powder, sugar, and salt into a bowl. Cut butter into flour mixture, using a pastry cutter. Add buttermilk until just combined.

Flour a work surface and, using your hands, bring dough together and fold 5 to 6 times, ending with a 1-inch thick rectangle.

Cut biscuits with a 2 1/2-inch biscuit cutter. Bring leftover dough together to be able to cut more biscuits.

Place biscuits into the air fryer basket and air-fry until golden brown, 8 to 10 minutes.