Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Dice the sweet potato into 1/2-inch cubes and chop the broccoli into bite-sized florets.
In a small mixing bowl, whisk together the olive oil, lemon juice, minced garlic, rosemary, thyme, sea salt, and black pepper to create the marinade.
Place the chicken breast, sweet potato cubes, and broccoli florets onto the prepared sheet pan.
Drizzle the lemon-herb marinade over the chicken and vegetables, using your hands or a spatula to toss the produce until every piece is well-coated.
Arrange the ingredients in a single layer, ensuring the chicken has enough space to roast evenly.
Roast for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender and slightly browned.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy.