Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel and dice the sweet potato into 1-inch cubes and slice the carrots into 1/2-inch thick rounds.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, combine the chicken breast, diced sweet potatoes, and carrots.
Drizzle with olive oil and add the minced garlic, rosemary, thyme, sea salt, and black pepper, tossing thoroughly to coat everything evenly.
Spread the chicken and vegetables in a single layer on the prepared baking sheet, ensuring they aren't overcrowded so they roast rather than steam.
Roast in the center of the oven for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are fork-tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy, then serve immediately with the roasted root vegetables.