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 cut into 1-inch cubes; peel the carrots and slice them into half-inch rounds.
Mince the garlic cloves finely.
In a large mixing bowl, combine the chicken breast, cubed sweet potatoes, and sliced 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 with your hands or a large spoon until the chicken and vegetables are evenly coated in the oil and seasonings.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the chicken pieces are not crowded by the vegetables.
Roast in the center of the oven for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the root vegetables are fork-tender and golden brown.
Remove from the oven and let the chicken rest for 5 minutes before slicing it to keep the juices intact.
Plate the sliced chicken alongside the roasted vegetables and serve immediately.