Preheat oven to 400°F and line a large baking sheet with parchment paper.
Dice the sweet potato into 1/2-inch cubes and chop the broccoli and bell pepper into bite-sized pieces.
Slice the chicken breast into even 1-inch strips for quick and even cooking.
In a large bowl, whisk together the olive oil, lemon juice, oregano, garlic powder, salt, and pepper.
Add the chicken and vegetables to the bowl, tossing thoroughly until every piece is coated in the savory herb marinade.
Spread the mixture in a single layer on the prepared baking sheet, ensuring space between pieces for optimal roasting.
Bake for 20-25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender.
Serve immediately, drizzling any remaining juices from the pan over the top for extra flavor.