Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel the sweet potato and cut it into uniform 1/2-inch cubes, then trim the ends off the fresh green beans.
Place the chicken breast, sweet potato cubes, and green beans onto the prepared baking sheet in a single layer.
Drizzle the olive oil and lemon juice over the chicken and vegetables.
Evenly sprinkle the garlic powder, smoked paprika, sea salt, and black pepper over all ingredients.
Toss the sweet potatoes and green beans to coat them in the oil and spices, and turn the chicken to ensure it is seasoned on both sides.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing it against the grain to serve.