Preheat oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch cubes and slice the zucchini and red bell pepper into similar sized pieces to ensure even cooking.
In a large mixing bowl, combine the chicken, zucchini, and bell peppers, then drizzle with lemon juice.
Sprinkle the sea salt, black pepper, dried oregano, and garlic powder over the mixture and toss thoroughly to coat every piece.
Spread the chicken and vegetables in a single layer on the baking sheet, ensuring they are not crowded so they roast rather than steam.
Roast in the center of the oven for 15 to 18 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender.
Serve immediately, drizzling any remaining juices from the pan over the top for extra flavor.