Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel and dice the sweet potato and carrots into 1/2-inch cubes; slice the bell pepper into strips and chop the broccoli into bite-sized florets.
Place the chicken breast in the center of the baking sheet and surround it with the prepared vegetables.
Drizzle the olive oil over the chicken and the vegetables, ensuring everything is lightly coated.
Whisk together the dried rosemary, thyme, garlic powder, sea salt, and black pepper in a small bowl, then sprinkle the mixture evenly over the entire tray.
Toss the vegetables with tongs to distribute the seasoning and flip the chicken to coat both sides.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are fork-tender and slightly charred.
Remove from the oven and let the chicken rest for 5 minutes before slicing it against the grain to maintain juiciness.
Plate the sliced chicken alongside the roasted vegetable medley and serve immediately.