Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Pat the chicken breast dry with a paper towel and cut into even 1-inch cubes to ensure uniform cooking.
Peel the sweet potato and cut into 1/2-inch cubes, then chop the broccoli into bite-sized florets and the bell pepper into 1-inch pieces.
In a large mixing bowl, combine the chicken, sweet potatoes, broccoli, and peppers with the olive oil, minced garlic, rosemary, thyme, salt, and pepper.
Toss everything thoroughly until the chicken and vegetables are well-coated in the oil and herb mixture.
Spread the mixture in a single layer on the prepared baking sheet, ensuring there is space between pieces so they roast rather than steam.
Roast for 20 to 25 minutes, tossing halfway through, until the chicken is cooked through and the sweet potatoes are golden and tender.