Preheat the oven to 350 degrees F.
Cut the red peppers in half and scoop out the seeds and ribs. Place them onto a baking sheet.
To the reserved brown rice mixture, stir in half the cheese and all the tomatoes. Stuff the peppers with the rice mixture, dividing it evenly. Top the peppers with the remaining cheese. Bake until the peppers are tender and the cheese has melted, 25 to 30 minutes.