Add the sausage, corn muffin mix, garlic powder, Italian seasoning, and dry mustard to a large mixing bowl. Use your hands or a rubber spatula to mix until evenly combined.
Add the shredded cheese to the bowl and mix into the sausage. (I highly recommend buying a block of cheese and shredding it yourself.)
Use a medium cookie scoop to portion the sausage mixture (about 1 1/2 tablespoons each). Use your hands to roll the scoops into balls and then place the meatballs into the air fryer basket. (You'll need to work in batches so you don't crowd the basket.)
Set your air fryer to 390 degrees F. Cook the meatballs for 3 minutes. Use tongs to flip the meatballs over, and then cook for another 3 minutes.
Remove the sausage balls from the air fryer and serve warm or at room temperature.
Notes
You can use Italian sausage instead of breakfast sausage for a different flavor. Try swapping out the cheddar cheese for mozzarella, too!
Putting parchment paper in the bottom of your air fryer basket is optional, but it makes it easier to rotate the meatballs midway through cooking. You can buy air fryer parchment paper or buy the regular rolls and cut it down to size.