Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Chop the sweet potato, broccoli, and red bell pepper into uniform bite-sized pieces for even cooking.
Slice the chicken breast into 1-inch cubes and place them in a large mixing bowl with the vegetables.
In a small jar, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Pour the lemon-herb dressing over the chicken and vegetables, tossing thoroughly to ensure every piece is coated.
Spread the mixture in a single layer on the prepared baking sheet, avoiding overcrowding.
Roast for 20 to 25 minutes until the chicken is cooked through and the vegetables are tender with lightly charred edges.