Preheat the oven to 375 degrees F (190 degrees C). Lightly grease a large baking sheet.
Mix Italian sausage, shredded mozzarella, baking mix, green bell pepper, yellow onion, ½ cup pizza sauce, garlic powder, Italian seasoning, salt, and ½ teaspoon pepper together in a large mixing bowl until well combined.
Roll sausage mixture into 1-inch balls; arrange on the prepared baking sheet.
Bake pizza balls in the preheated oven until lightly browned, about 23 to 25 minutes. Serve hot with remaining pizza sauce for dipping.
