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 along with the red onion into uniform 1-inch chunks to ensure even cooking.
Mince the garlic cloves finely and strip the leaves from the rosemary and thyme sprigs before chopping them.
In a large bowl, toss the prepared root vegetables with half of the olive oil, half of the garlic, and half of the chopped herbs.
Pat the chicken breast dry with a paper towel and rub both sides with the remaining olive oil, garlic, herbs, sea salt, and black pepper.
Place the chicken in the center of the baking sheet and arrange the vegetable mixture in a single layer around it.
Roast for 25 to 30 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 the meat succulent and juicy.