Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Trim the ends of the Brussels sprouts and slice them in half, then dice the chicken breast into 1-inch bite-sized pieces.
In a large bowl, toss the chicken and Brussels sprouts with olive oil, sea salt, black pepper, and garlic powder until evenly coated.
Spread the mixture in a single layer on the prepared baking sheet, ensuring they aren't crowded to allow for maximum crisping.
Roast for 20-25 minutes, tossing halfway through, until the chicken is cooked through and the sprouts are golden brown.
While roasting, whisk together the balsamic vinegar and honey in a small bowl to create the glaze.
Drizzle the balsamic mixture over the hot chicken and sprouts immediately after removing them from the oven, tossing to glaze before serving.