Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Cut the chicken breast into bite-sized pieces and place them in a large mixing bowl.
Add the broccoli florets, sliced zucchini, and cubed sweet potato to the bowl with the chicken.
In a small jar, whisk together the olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Pour the marinade over the chicken and vegetables, tossing thoroughly to ensure every piece is well-coated.
Spread the mixture in a single layer on the prepared baking sheet, ensuring nothing is overcrowded.
Bake for 20-25 minutes, or until the chicken is cooked through and the vegetables are tender and lightly browned.
Serve immediately, garnished with fresh herbs or an extra squeeze of lemon if desired.