Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel the sweet potato and cut into 1/2-inch cubes, then chop the red bell pepper into bite-sized pieces.
Place the chicken breast, sweet potato cubes, broccoli florets, and bell peppers onto the prepared baking sheet in a single layer.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb mixture over the chicken and vegetables, tossing the produce and coating the chicken thoroughly.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are tender and slightly caramelized.
Remove from the oven and let the chicken rest for 5 minutes before slicing to ensure maximum juiciness.