Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and set aside.
Chop the broccoli, red bell pepper, and zucchini into uniform pieces to ensure they roast evenly.
In a large mixing bowl, whisk together the olive oil, lemon juice, lemon zest, oregano, garlic powder, sea salt, and black pepper.
Add the chicken and chopped vegetables to the bowl and toss thoroughly until every piece is coated in the lemon-herb marinade.
Spread the mixture in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly charred edges.
Remove from the oven and serve immediately while hot.