Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Cut the chicken breast into 1-inch cubes and chop the broccoli, bell pepper, and carrots into bite-sized pieces.
In a small bowl, whisk together the olive oil, fresh lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken and vegetables in a large mixing bowl and pour the lemon-herb dressing over them, tossing until everything is thoroughly coated.
Spread the mixture in a single, even layer on the prepared baking sheet to ensure even roasting.
Bake for 20-25 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.