Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Wash and peel the sweet potato, then cut it into 1/2-inch cubes. Trim the tough, woody ends off the asparagus spears.
In a small glass bowl, whisk together the olive oil, lemon juice, lemon zest, minced rosemary, garlic powder, sea salt, and black pepper to create the marinade.
Place the chicken breast on one side of the sheet pan and arrange the sweet potato cubes and asparagus on the other side.
Drizzle the lemon-herb mixture over the chicken and vegetables, using your hands or a brush to ensure everything is evenly coated.
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 to ensure the juices redistribute for a moist finish.