Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Prepare the vegetables by peeling the carrots and parsnips, then slicing them into 1/2-inch thick rounds or uniform sticks.
In a large mixing bowl, combine the chicken thighs, sliced carrots, and sliced parsnips.
Drizzle the olive oil over the chicken and vegetables, then sprinkle with the rosemary, thyme, garlic powder, sea salt, and black pepper.
Toss everything together thoroughly with your hands or tongs until the chicken and vegetables are evenly coated in the oil and spices.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the chicken pieces are not touching to allow for proper browning.
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 fork-tender and caramelized.
Remove from the oven and let the chicken rest for 5 minutes before serving to keep it juicy and flavorful.