Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and halve the baby potatoes so they cook evenly.
Place the chicken, halved potatoes, broccoli florets, and sliced bell peppers onto the prepared sheet pan.
In a small bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Drizzle the lemon-herb mixture over the chicken and vegetables, tossing thoroughly with your hands or tongs to coat every piece.
Spread the ingredients into a single, even layer across the pan to ensure they roast and crisp rather than steam.
Bake for 22 to 25 minutes until the chicken is cooked through and the potatoes are golden and fork-tender.