Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Pat the chicken breast dry with a paper towel and cut into uniform 1-inch cubes for even roasting.
In a large mixing bowl, whisk together the extra virgin olive oil, lemon juice, minced garlic, rosemary, salt, and pepper.
Add the chicken cubes, broccoli, carrots, and zucchini to the bowl, tossing until every piece is thoroughly coated in the herb mixture.
Spread the chicken and vegetables in a single layer on the prepared baking sheet, ensuring they are not crowded to allow for proper browning.
Roast for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.
Remove from the oven and let the chicken rest for 2 minutes before serving to keep it juicy and flavorful.