Preheat oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Dice the chicken breast into even 1-inch pieces and chop the broccoli, bell pepper, and zucchini into bite-sized chunks.
In a large bowl, whisk together the olive oil, lemon juice, rosemary, thyme, garlic powder, salt, and pepper until well combined.
Add the chicken and vegetables to the bowl, tossing thoroughly to ensure every piece is coated in the aromatic herb oil.
Spread the mixture across the baking sheet in a single layer, ensuring no overcrowding to allow for proper browning.
Roast for 20 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.