Preheat air fryer to 375°F (190°C). Cut puff pastry into 1-inch strips, then into bite-size pieces.

Toss pieces lightly with melted butter. Mix sugar and cinnamon in a bowl.

Place bites in a single layer in the air fryer basket, not touching. Cook 6–8 minutes, shaking halfway, until puffed and golden.

Immediately toss hot bites in the cinnamon sugar. Serve warm.