Preheat your oven to 400°F (200°C) and line a sheet pan with parchment paper.
In a small bowl, mix together lemon juice, olive oil, garlic powder, dried oregano, salt, and pepper to create a marinade.
Place the chicken breast in a shallow dish and pour half of the marinade over it, ensuring it’s evenly coated. Let it marinate while you prep the vegetables.
Wash and cut the broccoli into bite-sized florets, and cube the sweet potato into 1-inch pieces.
On the prepared sheet pan, spread the broccoli and sweet potatoes evenly. Drizzle the remaining marinade over the vegetables and toss to coat.
Place the marinated chicken breast on the same sheet pan, ensuring even spacing among the vegetables.
Bake in the preheated oven for 20-25 minutes, or until the chicken is cooked through (internal temperature reaches 165°F) and the vegetables are tender and slightly caramelized.
Remove from the oven, let rest for a few minutes, then slice the chicken and serve alongside the roasted broccoli and sweet potatoes.