Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Chop the chicken breast into 1-inch bite-sized pieces and halve the baby potatoes to ensure even cooking.
In a small bowl, whisk together the olive oil, lemon juice, minced garlic, oregano, sea salt, and black pepper.
Place the chicken, potatoes, broccoli florets, and sliced bell peppers onto the prepared sheet pan.
Pour the lemon-herb dressing over the ingredients and toss thoroughly with your hands or tongs to ensure an even coating.
Spread everything out into a single layer, ensuring the chicken and vegetables aren't overcrowded so they roast properly.
Bake for 22-25 minutes, or until the chicken is cooked through and the potatoes are fork-tender and slightly browned.
Remove from the oven and serve immediately, finishing with an extra squeeze of fresh lemon if desired.