Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch cubes and chop the broccoli, bell peppers, and carrots into uniform, bite-sized pieces.
In a small mixing bowl, whisk together the extra virgin olive oil, fresh lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken and all the vegetables onto the prepared sheet pan and drizzle the lemon-herb marinade over the top.
Toss everything together with your hands or tongs until every piece is thoroughly and evenly coated with the oil and spices.
Spread the mixture out into a single layer, ensuring the chicken pieces aren't touching too much so they can brown properly.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.
Remove from the oven and let rest for 2 minutes before serving to allow the juices to redistribute.