Preheat your air fryer to 350 for at least 3 minutes, or according to your manufacturers instructions.
Split the english muffins using a fork or a butter knife, and place them, cut sides up, on a baking sheet or plate. Only prepare as many english muffin pizzas as you can fit in the air fryer at once. This will help the pizza stay crispy, preventing them from sitting too long with the moist ingredients.
Spoon 1-2 tablespoons of pizza sauce onto each english muffin half. Use the back of the spoon to spread it evenly over the bread.
Top each half with a small portion of shredded cheese, about ¼ cup.
Place the prepared english muffin pizzas into the air fryer and cook at 350F for 4-6 minutes, or until the cheese is melted and bubbly and the bread is toasted.
Top with 2-3 slices of pepperoni and return to the air fryer for 1-2 minutes. Remove the air fryer basket and quickly adjust any pepperoni slices that have flown off of the pizzas. If you would like to add any other toppings, do so at the same time you add the pepperoni.
Remove the pizzas from the air fryer and let cool for 5 minutes before serving.
Repeat the process with the remaining english muffins, working in batches until all of the muffins have been used up.