Preheat oven to 400°F and line a large baking sheet with parchment paper.
Dice the chicken breast into 1-inch cubes and chop the sweet potatoes into small 1/2-inch pieces to ensure even cooking.
In a large mixing bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the cubed chicken, sweet potatoes, broccoli florets, and sliced bell peppers to the bowl, tossing thoroughly until every piece is coated in the herb mixture.
Spread the chicken and vegetables in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the edges can crisp up.
Roast for 20-25 minutes, tossing the ingredients halfway through, until the chicken is fully cooked and the vegetables are tender with golden-brown edges.