Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Slice the chicken breast into even 1-inch cubes and place them in a large mixing bowl.
Chop the zucchini into half-moons and the red bell pepper into bite-sized squares, then add them to the bowl with the broccoli florets.
In a small jar or bowl, whisk together the extra virgin olive oil, fresh lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Pour the lemon-herb marinade over the chicken and vegetables, tossing thoroughly to ensure every piece is well-coated.
Spread the mixture out in a single layer on the prepared sheet pan, ensuring there is space between items so they roast rather than steam.
Place the pan in the oven and bake for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender-crisp.
Remove from the oven and let rest for 5 minutes before portioning into meal prep containers.