Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and place them in a large mixing bowl.
Chop the sweet potato, zucchini, and red bell pepper into 1-inch pieces, then break the broccoli into small, bite-sized florets.
In a small jar or bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, oregano, thyme, sea salt, and black pepper.
Add all the chopped vegetables to the bowl with the chicken and pour the lemon-herb dressing over the top.
Toss everything thoroughly until the chicken and vegetables are evenly coated with the herb mixture.
Spread the mixture in a single, even layer across the prepared sheet pan, ensuring pieces are not overlapping so they roast properly.
Bake for 20-25 minutes until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.
Remove from the oven and serve immediately, optionally finishing with an extra squeeze of fresh lemon juice.