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 bite-sized pieces and place them into a large mixing bowl.
Prepare the vegetables by cutting the zucchini into half-moons and the red bell pepper into thin strips; add them to the bowl with the broccoli florets.
In a small bowl, whisk together the extra virgin olive oil, fresh lemon juice, dried oregano, garlic powder, sea salt, and black pepper until well combined.
Pour the marinade over the chicken and vegetables, tossing thoroughly with your hands or a large spoon to ensure every piece is evenly coated.
Spread the mixture out in a single layer on the prepared sheet pan, making sure not to overcrowd the pan so the vegetables roast instead of steam.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly browned edges.
Remove from the oven and let rest for 2 minutes before serving to allow the juices to redistribute.