Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel the sweet potato and carrots, then chop them into uniform 1-inch cubes to ensure they roast evenly.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, combine the chicken breast, cubed sweet potatoes, and carrots.
Drizzle the olive oil over the chicken and vegetables, then add the minced garlic, rosemary, thyme, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are well-coated in the oil and herb mixture.
Spread the ingredients in a single layer on the prepared baking sheet, making sure not to overcrowd the pan.
Roast for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the root vegetables are tender and golden brown.
Remove from the oven and let the chicken rest for 5 minutes before slicing to retain its juices, then serve immediately.