Preheat your oven to 400°F and line a rimmed baking sheet with parchment paper for easy cleanup.
Dice the chicken breast into 1-inch pieces and chop the broccoli and bell peppers into uniform, bite-sized florets and strips.
In a large mixing bowl, whisk together the olive oil, lemon juice, lemon zest, oregano, garlic powder, salt, and pepper.
Add the chicken and vegetables to the bowl, tossing well to ensure every piece is coated in the aromatic herb mixture.
Spread the ingredients in a single layer on the baking sheet, avoiding overcrowding to ensure they roast rather than steam.
Bake for 20 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender-crisp.
Serve warm, garnished with extra fresh herbs if desired for a clean and satisfying meal.