Preheat the oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into even 1-inch pieces and chop the broccoli, bell pepper, and carrots into bite-sized chunks.
Place the chicken and vegetables on the prepared baking sheet in a single layer.
In a small bowl, whisk together the olive oil, lemon juice, minced garlic, oregano, salt, and pepper.
Pour the lemon-herb mixture over the chicken and vegetables, tossing thoroughly to ensure every piece is well-coated.
Roast in the oven for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are tender and slightly caramelized.
Serve immediately while hot for the best texture and flavor.