Preheat oven to 400°F and line a large baking sheet with parchment paper.
Dice the sweet potato into 1/2-inch cubes and chop the broccoli into bite-sized florets.
Place the chicken breast, sweet potatoes, and broccoli on the prepared pan.
In a small bowl, whisk together the olive oil, lemon juice, rosemary, garlic powder, salt, and pepper.
Drizzle the lemon-herb mixture over the chicken and vegetables, tossing well to ensure everything is evenly coated.
Spread the ingredients in a single layer, ensuring the chicken has space to roast properly.
Bake for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.
Let the chicken rest for 5 minutes before slicing to keep it juicy.