Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast, zucchini, red bell pepper, and sweet potato into uniform 1-inch cubes to ensure they cook at the same rate.
In a small glass jar or bowl, whisk together the extra virgin olive oil, lemon juice, oregano, garlic powder, sea salt, and black pepper.
Place the chicken cubes and all the chopped vegetables onto the prepared baking sheet and pour the lemon-herb dressing over the top.
Use your hands or a spatula to toss everything together until every piece is thoroughly coated in the herb mixture.
Spread the ingredients out in a single layer, making sure not to crowd the pan so the vegetables roast and brown rather than steam.
Bake for 22-25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.