Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into uniform 1-inch cubes to ensure even cooking.
Chop the broccoli into small florets, slice the bell pepper into strips, and dice the red onion.
In a large mixing bowl, combine the chicken cubes, broccoli, peppers, and onions.
Mince the garlic and add it to the bowl along with the olive oil, oregano, thyme, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are well coated in the oil and spices.
Spread the mixture in a single layer on the prepared baking sheet, ensuring nothing is overcrowded so the vegetables roast rather than steam.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender with slightly charred edges.
Remove from the oven and let rest for 2 minutes before serving.