Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and place them in a large mixing bowl.
Chop the broccoli into bite-sized florets and slice the red bell pepper into 1-inch pieces, adding them to the bowl with the chicken.
In a small jar or bowl, whisk together the olive oil, lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper.
Pour the marinade over the chicken and vegetables, tossing thoroughly to ensure every piece is well-coated.
Spread the mixture in a single layer on the prepared sheet pan, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly charred edges.