Preheat your oven to 400°F (200°C) and line a large 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 chopping the zucchini into half-moons and the red bell pepper into 1-inch squares.
Add the broccoli florets, zucchini, and bell pepper to the bowl with the chicken.
In a small glass jar or bowl, whisk together the olive oil, lemon juice, minced garlic, oregano, thyme, salt, and pepper.
Pour the herb dressing over the chicken and vegetables, tossing thoroughly with your hands or tongs to ensure an even coating.
Spread the mixture in a single layer across the prepared sheet pan, ensuring the ingredients are not crowded so they roast rather than steam.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is cooked through and the vegetables have developed golden, caramelized edges.