In a saucepan over medium heat, combine water, butter, sugar, and salt. Bring to a boil.
Reduce heat and stir in flour until a dough forms and pulls away from the sides.
Remove from heat and let cool for 10 minutes.
Add eggs one at a time, mixing thoroughly after each addition until smooth.
Transfer dough to a piping bag fitted with a star tip.
Line air fryer basket with parchment and lightly spray with cooking spray.
Pipe 1- to 2-inch dough segments directly into the basket.
Air fry at 375°F (190°C) for 10–12 minutes until golden brown.
Mix sugar and cinnamon in a bowl. Toss warm churro bites in the mixture until fully coated.
Serve warm and enjoy!