Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into uniform 1-inch cubes and chop the broccoli, bell pepper, and zucchini into bite-sized pieces.
In a large mixing bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken cubes and chopped vegetables to the bowl, tossing thoroughly until every piece is evenly coated with the herb mixture.
Spread the chicken and vegetables in a single layer on the prepared baking sheet, ensuring they are not overcrowded to allow for proper roasting.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly browned edges.
Remove from the oven and serve immediately while hot, perhaps with an extra squeeze of fresh lemon for added brightness.