Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch cubes and dice the sweet potato into small half-inch pieces to ensure they cook at the same rate.
Chop the broccoli into bite-sized florets and the red bell pepper into 1-inch squares.
Place the chicken, sweet potatoes, broccoli, and bell peppers onto the prepared sheet pan.
In a small bowl, whisk together the olive oil, lemon juice, oregano, garlic powder, sea salt, and black pepper.
Drizzle the herb oil over the chicken and vegetables, then toss thoroughly with your hands or tongs to ensure every piece is well-coated.
Spread the mixture out into a single, even layer across the pan, avoiding overcrowding so the vegetables roast rather than steam.
Bake for 20 to 25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender and slightly caramelized.
Remove from the oven and let rest for 2 minutes before serving or portioning into meal prep containers.