Wash the bell peppers and cut off their tops. Remove the stems, seeds, and membranes, then lightly brush the outsides with olive oil if desired.

Cook the ground meat and diced onion in a skillet over medium heat for about 6–8 minutes, stirring and breaking the meat into small pieces, until it is no longer pink. Drain any excess fat.

Add the minced garlic and cook for about 30 seconds, just until fragrant. Stir in the cooked rice, tomato sauce or diced tomatoes, Italian seasoning, salt, and black pepper.

Heat the filling until it is hot and well combined. Preheat the air fryer to 350°F (175°C) if your model requires preheating.

Spoon the hot filling into the prepared peppers, packing it lightly rather than pressing it down firmly. Place the peppers upright in the air fryer basket, using a small heatproof dish or arranging them snugly if they tend to tip.

Air-fry the stuffed peppers at 350°F for approximately 12–15 minutes, until the pepper shells begin to soften and the filling is hot.

Sprinkle the shredded cheese over the tops. Air-fry for another 2–4 minutes, until the cheese is melted and lightly browned.

Let the peppers rest for 2–3 minutes before serving. This brief rest allows the filling to settle and makes the peppers easier to transfer.