Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Scrub the potato clean and dice it into 1/2-inch cubes, ensuring they are uniform in size for even roasting.
Cut the chicken breast into 1-inch pieces and trim any excess fat to keep the protein lean and clean.
Chop the broccoli into small florets, including the tender parts of the stems for added texture and fiber.
In a large mixing bowl, combine the diced chicken, potatoes, and broccoli florets.
Drizzle the mixture with olive oil and sprinkle evenly with dried rosemary, garlic powder, sea salt, and black pepper.
Toss everything thoroughly until every piece is well-coated in the herb-infused oil.
Spread the mixture in a single layer on the prepared baking sheet, ensuring no crowding to allow for proper crisping.
Roast for 22-25 minutes, flipping the ingredients halfway through, until the chicken is cooked through and the potatoes are tender.
Finish with a fresh squeeze of lemon juice to brighten the earthy herb flavors before serving.