Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Cut the chicken breast into 1-inch bite-sized pieces and slice the red bell pepper into thin strips.
Place the chicken, broccoli florets, and bell peppers onto the prepared sheet pan.
In a small bowl, whisk together the olive oil, lemon juice, oregano, garlic powder, salt, and pepper.
Drizzle the marinade over the chicken and vegetables, tossing well to ensure everything is evenly coated.
Spread the ingredients into a single layer to ensure even roasting and browning.
Bake for 18-22 minutes, or until the chicken is cooked through and the vegetables are tender-crisp.
Remove from the oven and serve immediately, optionally garnishing with fresh lemon zest for extra brightness.