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 into small 1/2-inch cubes, and break the broccoli into bite-sized florets.
Place the chicken breast, sweet potato cubes, and broccoli florets onto the prepared sheet pan in a single layer.
Drizzle the olive oil and fresh lemon juice over the chicken and vegetables.
Evenly sprinkle the dried oregano, garlic powder, sea salt, and black pepper over all components on the tray.
Toss the vegetables with your hands or tongs to ensure they are well-coated, and flip the chicken to season both sides.
Roast in the oven 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 let the chicken rest for 5 minutes before slicing to keep it juicy.