Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel and slice the carrots and parsnips into uniform 1-inch rounds to ensure even roasting.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, rosemary, thyme, salt, and pepper.
Place the sliced root vegetables on the prepared sheet pan and drizzle with half of the lemon-herb mixture, tossing well to coat.
Arrange the chicken breasts on the pan, nestling them among the vegetables, and brush the remaining marinade over the top of each breast.
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 vegetables are tender.
Let the chicken rest for 5 minutes before serving to ensure the juices remain locked inside for a moist finish.