Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Peel the sweet potato and cut it into 1/2-inch cubes, then chop the broccoli into bite-sized florets.
Place the chicken breast in the center of the baking sheet and arrange the sweet potatoes and broccoli around it in a single layer.
In a small glass jar or bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb mixture over the chicken and vegetables, using a brush or clean hands to ensure everything is evenly coated.
Bake for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are tender when pierced with a fork.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it moist and tender.