Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Cut the chicken breast into one-inch cubes and slice the bell pepper and zucchini into similar bite-sized pieces.
Place the chicken, broccoli, bell pepper, and zucchini onto the prepared baking sheet.
In a small bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb mixture over the chicken and vegetables, tossing thoroughly with your hands or tongs to coat every piece.
Spread the ingredients out into a single layer to ensure even roasting and prevent steaming.
Bake for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender with slightly browned edges.