Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel the carrots and parsnips, then dice them into uniform 1/2-inch cubes to ensure even roasting.
In a large mixing bowl, combine the diced carrots and parsnips with the olive oil, rosemary, thyme, garlic powder, sea salt, and black pepper.
Toss the vegetables thoroughly until every piece is well-coated with the oil and herb mixture.
Spread the vegetables in a single layer on the prepared baking sheet, ensuring they are not crowded so they roast rather than steam.
Roast for 25 to 30 minutes, tossing halfway through, until the vegetables are tender and have developed golden, caramelized edges.
While the vegetables roast, remove the skin from the rotisserie chicken and slice or shred the breast meat into thin strips.
During the final 5 minutes of roasting, place the chicken on the baking sheet alongside the vegetables to warm it through.
Remove from the oven and divide the herb-roasted vegetables and chicken onto plates to serve immediately.