Preheat your oven to 425°F (220°C) and line a large sheet pan with parchment paper for easy cleanup.
Dice the chicken breast into even 1-inch cubes and chop the broccoli, bell pepper, and zucchini into bite-sized pieces.
In a large mixing bowl, combine the chicken and vegetables, then drizzle with olive oil and sprinkle with oregano, garlic powder, salt, and pepper.
Toss the mixture thoroughly to ensure every piece is well-coated with the herb-infused oil.
Spread the ingredients in a single layer on the prepared pan, making sure not to overcrowd so they roast to a perfect crisp.
Bake for 20 to 25 minutes, giving the pan a good shake halfway through, until the chicken is cooked and the veggies are tender.
Finish by sprinkling the fresh parsley over the hot medley before serving immediately.