Melt butter in a saucepan over medium-high heat. Pour in milk and add salt. Lower heat to medium and bring to a boil, continuously stirring with a wooden spoon. Quickly add flour all at once. Keep stirring until the dough comes together.
Remove from heat and let cool for 5 to 7 minutes. Mix in eggs with the wooden spoon until choux pastry comes together. Spoon dough into a pastry bag fitted with a large star tip. Pipe dough into strips straight into the air fryer basket.
Air fry churros at 340°F for 5 minutes Flip and cook 4 to 5 minutes until golden brown.
Meanwhile combine sugar and cinnamon in a small bowl and onto a shallow plate.
Remove fried churros from air fryer and roll in the cinnamon-sugar mixture.