Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Trim and halve the brussels sprouts, slice the carrots into half-inch rounds, and cut the red onion into thick wedges.
Pat the chicken breast dry with paper towels and cut into one-inch bite-sized pieces to ensure even cooking with the vegetables.
In a large mixing bowl, combine the chicken pieces, brussels sprouts, carrots, and red onion wedges.
Drizzle the extra virgin olive oil over the mixture and sprinkle with dried rosemary, dried thyme, garlic powder, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are evenly coated in the oil and herb seasoning.
Spread the mixture in a single layer on the prepared baking sheet, ensuring nothing is overcrowded so the vegetables can properly caramelize.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are tender and golden brown.
Remove from the oven and let rest for two minutes before serving to keep the chicken juicy.