Preheat your oven to 400°F and line a large rimmed sheet pan with parchment paper for easy cleanup.
Dice the chicken breast into 1-inch pieces and cut the sweet potato into 1/2-inch cubes to ensure they cook evenly.
In a small glass bowl, whisk together the extra virgin olive oil, lemon juice, oregano, garlic powder, sea salt, and black pepper.
Place the chicken, sweet potato cubes, broccoli florets, and sliced bell peppers onto the prepared sheet pan.
Pour the lemon-herb dressing over the chicken and vegetables, then toss with your hands or tongs until every piece is well coated.
Spread the ingredients out into a single layer, ensuring there is space between them so they roast rather than steam.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender.