Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Dice the sweet potato into 1/2-inch cubes and place them on one side of the baking sheet.
Pat the chicken breast dry with a paper towel and place it in the center of the sheet.
In a small bowl, whisk together the olive oil, lemon zest, lemon juice, chopped rosemary, garlic powder, salt, and pepper.
Drizzle half of the lemon-herb mixture over the chicken and sweet potatoes, tossing the potatoes to coat evenly.
Roast for 15 minutes, then add the broccoli florets to the remaining space on the baking sheet.
Drizzle the remaining herb mixture over the broccoli and continue roasting for another 10-12 minutes until the chicken reaches an internal temperature of 165°F.
Let the chicken rest for 5 minutes before slicing to ensure it stays juicy and flavorful.