Preheat your oven to 400°F and line a large rimmed sheet pan with parchment paper for easy cleanup.
Peel and dice the sweet potato into 1/2-inch cubes and cut the chicken breast into bite-sized pieces.
In a small mixing bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, oregano, sea salt, and black pepper.
Place the chicken, sweet potatoes, broccoli florets, and sliced bell peppers onto the prepared sheet pan.
Pour the lemon-garlic dressing over the chicken and vegetables, tossing thoroughly with your hands or tongs to ensure an even coating.
Spread the ingredients into a single layer, making sure not to overcrowd the pan so the components can crisp properly.
Roast for 20 to 25 minutes, tossing the ingredients halfway through, until the chicken is cooked through and the sweet potatoes are golden and tender.