Preheat oven to 400°F and line a large sheet pan with parchment paper.
Cut the chicken breast into 1-inch bite-sized pieces and halve the baby potatoes.
Chop the broccoli into florets, slice the bell pepper into strips, and slice the zucchini into rounds.
In a large bowl, whisk together the olive oil, lemon juice, oregano, garlic powder, sea salt, and black pepper.
Add the chicken and all vegetables to the bowl and toss until everything is evenly coated in the herb marinade.
Spread the mixture in a single layer on the prepared sheet pan, ensuring pieces aren't overcrowded.
Roast for 20-25 minutes, or until the chicken is cooked through and the potatoes are fork-tender.
Serve immediately, drizzled with any remaining juices from the pan for extra brightness.