Preheat the oven to 400°F (200°C) and line a large baking sheet with parchment paper.
In a large mixing bowl, toss the halved Brussels sprouts with olive oil, salt, and black pepper until evenly coated.
Spread the Brussels sprouts in a single layer on the prepared baking sheet, ensuring they are not overcrowded.
Roast in the preheated oven for 20–25 minutes, flipping halfway through, until the sprouts are tender and the edges are golden brown and slightly crispy.
Remove the baking sheet from the oven and drizzle the roasted Brussels sprouts with balsamic vinegar, tossing gently to coat.
Transfer to a serving dish and serve immediately while warm.