Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast, red bell pepper, and sweet potato into uniform 1-inch cubes to ensure even roasting.
In a large mixing bowl, whisk together the olive oil, fresh lemon juice, minced garlic, rosemary, thyme, salt, and pepper.
Add the chicken, broccoli, peppers, and sweet potatoes to the bowl and toss thoroughly until every piece is well-coated.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the pieces are not overcrowded.
Bake for 20 to 25 minutes, or until the chicken is cooked through and the vegetables have slightly caramelized edges.
Remove from the oven and serve immediately with an optional extra squeeze of fresh lemon.