Preheat the oven to 400°F and line a large baking sheet with parchment paper.
Slice the red bell pepper and zucchini into uniform bite-sized pieces and break the broccoli into small florets.
In a small bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken breast on one side of the baking sheet and spread the vegetables across the remaining space.
Pour the lemon-herb dressing over the chicken and vegetables, using your hands or a brush to ensure everything is evenly coated.
Bake for 20 to 22 minutes, or until the chicken is cooked through to 165°F and the vegetables are tender with slightly browned edges.
Allow the chicken to rest for 5 minutes before slicing it into strips to serve alongside the roasted vegetables.