Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper.
In a small mixing bowl, whisk together the olive oil, fresh lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper until the marinade is emulsified.
Place the chicken breast, broccoli florets, and sliced carrots onto the prepared sheet pan.
Drizzle the lemon-herb marinade over the chicken and vegetables, tossing thoroughly with tongs to ensure every piece is well-coated.
Spread the ingredients out into a single layer, making sure the chicken has enough space around it to roast evenly rather than steam.
Roast for 20 to 25 minutes, or until the chicken is cooked through to an internal temperature of 165°F and the vegetables are fork-tender with golden edges.
Remove the pan from the oven and allow the chicken to rest for 5 minutes before slicing to ensure the juices stay locked in.