Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Pat the chicken breast dry with a paper towel to ensure the spice rub adheres and the meat browns beautifully.
In a small bowl, whisk together the garlic powder, smoked paprika, sea salt, and black pepper.
Rub the chicken breast with half of the olive oil and the spice mixture until it is evenly coated on all sides.
Peel and cube the sweet potato into half-inch pieces, then toss them and the broccoli florets with the remaining olive oil and a pinch of salt on the baking sheet.
Arrange the chicken and vegetables in a single layer, ensuring they are spread out to allow for even roasting and caramelization.
Bake 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 drizzle the chicken with fresh lemon juice to brighten the flavors before serving.