Preheat oven to 425 degrees F (220 degrees C). Line a 9x13-inch baking pan with aluminum foil.
Combine olive oil, salt, pepper, and carrots in a bag; toss to coat. I use the carrot bag. Pour the carrots into the prepared baking pan.
Bake in the preheated oven until tender, about 30 minutes. Sprinkle the balsamic vinegar over the carrots; shake the pan to coat evenly. Return to over and bake until the liquid is absorbed, 5 to 10 minutes. Serve hot.