Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Peel the sweet potato and cut it into 1-inch cubes, then trim the tough woody ends off the asparagus spears.
Place the chicken breast, sweet potato cubes, and asparagus spears in a single layer on the prepared baking sheet.
Drizzle the olive oil and lemon juice evenly over the chicken and vegetables.
Sprinkle the dried rosemary, garlic powder, sea salt, and black pepper over everything on the pan.
Toss the vegetables with your hands or tongs to coat them thoroughly, and flip the chicken to ensure it is seasoned on both sides.
Roast 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 it remains juicy and tender.