Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Peel the sweet potato and cut it into 1-inch cubes, then chop the broccoli into bite-sized florets.
Place the chicken breast, sweet potato cubes, and broccoli on the prepared baking sheet.
In a small bowl, whisk together the olive oil, juice from half a lemon, dried rosemary, garlic powder, sea salt, and black pepper.
Drizzle the herb mixture over the chicken and vegetables, tossing well to ensure everything is evenly coated.
Roast in the oven for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are golden and tender.
Let the chicken rest for 5 minutes before slicing to keep it juicy, then serve immediately.