Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
In a small mixing bowl, whisk together the olive oil, balsamic vinegar, dried oregano, garlic powder, sea salt, and black pepper until well combined.
Prepare the vegetables by chopping the red bell pepper into bite-sized pieces and slicing the zucchini into half-moons.
Place the chicken breast, broccoli florets, bell pepper, and zucchini onto the prepared sheet pan.
Pour the herb marinade over the chicken and vegetables, then toss thoroughly with your hands or tongs to ensure every piece is evenly coated.
Spread the ingredients out into a single layer, ensuring the chicken is in the center and not covered by vegetables.
Roast in the oven for 20 to 25 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 the chicken rest for 5 minutes before slicing to keep it juicy.