Preheat oven to 425°F and place a pizza stone or baking sheet in the oven.
Place the 12-inch pre-made pizza crust onto the hot pizza stone or baking sheet.
Spoon the pizza sauce evenly over the crust, leaving a ½-inch border around the edge.
Sprinkle the shredded mozzarella cheese evenly over the sauce.
Arrange the sliced pepperoni over the cheese.
Scatter the sliced fresh mushrooms over the pepperoni.
Bake for 12–15 minutes, until the crust is golden brown and the cheese is bubbly and lightly browned.
Remove the pizza from the oven and let cool for 5 minutes before slicing and serving.