Preheat oven to 375°F. Cut the tops off the bell peppers and remove seeds and membranes. Place peppers in a baking dish.
In a large skillet over medium heat, cook ground beef until browned. Add onion and garlic, cooking until onion is soft, about 5 minutes.
Drain any excess fat and stir in cooked rice, diced tomatoes, Italian seasoning, salt, and pepper. Mix well.
Remove from heat and stir in half of the shredded cheese.
Spoon the filling mixture into each pepper, packing it down gently. Pour tomato sauce over the tops.
Cover the baking dish with foil and bake for 35 minutes.
Remove foil, sprinkle remaining cheese on top of each pepper, and bake uncovered for another 10 minutes until cheese is melted and bubbly.
Let cool for 5 minutes before serving. Enjoy these delicious stuffed peppers!