Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Dice the chicken breast and sweet potato into 1-inch cubes, slice the carrots into rounds, and chop the zucchini into half-moons.
In a small glass jar or bowl, whisk together the olive oil, lemon juice, oregano, thyme, garlic powder, sea salt, and black pepper until emulsified.
Place the chicken pieces and all the chopped vegetables into a large mixing bowl, pour the herb dressing over the top, and toss thoroughly to ensure every piece is well-coated.
Spread the mixture out in a single, even layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast properly.
Bake for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender with golden edges.