Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Dice the sweet potato into half-inch cubes and cut the chicken breast into uniform bite-sized pieces.
Place the chicken, sweet potato cubes, broccoli florets, and sliced bell peppers onto the prepared sheet pan.
In a small jar or bowl, whisk together the olive oil, lemon juice, lemon zest, oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb dressing over the chicken and vegetables, tossing everything well with your hands to ensure an even coating.
Spread the mixture into a single layer across the pan, making sure not to overcrowd the ingredients so they roast beautifully.
Bake for 20 to 25 minutes until the chicken is fully cooked and the sweet potatoes are tender and golden on the edges.