Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Prepare the vegetables by trimming and halving the Brussels sprouts, slicing the carrot into rounds, and cutting the red onion into thick wedges.
Place the chicken breast and the prepared vegetables onto the baking sheet in a single layer.
In a small bowl, whisk together the olive oil, minced garlic, dried rosemary, dried thyme, sea salt, and black pepper.
Drizzle the herb oil mixture over the chicken and vegetables, using your hands or tongs to toss everything until thoroughly and evenly coated.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and golden.
Remove from the oven and allow the chicken to rest for 5 minutes before slicing to ensure it stays moist and flavorful.