Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into uniform 1-inch pieces and place them in a large mixing bowl.
Add the broccoli florets, sliced bell peppers, and sliced zucchini to the bowl with the chicken.
In a small separate bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb dressing over the chicken and vegetables, tossing thoroughly to ensure every piece is well-coated.
Spread the mixture in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken reaches an internal temperature of 165°F.
Remove from the oven and serve immediately while the chicken is juicy and the vegetables are perfectly tender.