Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel and slice the carrots and parsnips into 1/2-inch thick rounds, and cut the red onion into small wedges.
In a small mixing bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, rosemary, thyme, salt, and pepper.
Place the chicken breast and the prepared vegetables onto the baking sheet in a single layer.
Pour the lemon-herb marinade over the chicken and vegetables, tossing them thoroughly to ensure everything is evenly coated.
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 and golden.
Let the chicken rest for 5 minutes before slicing to keep it juicy, then serve alongside the roasted roots.