Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Slice the chicken breast into 1-inch bite-sized cubes and place them in a large mixing bowl.
Chop the broccoli into small florets, seed and dice the red bell pepper, and slice the zucchini into half-moons.
In a small jar or bowl, whisk together the extra virgin olive oil, fresh lemon juice, dried oregano, garlic powder, sea salt, and black pepper until well combined.
Add all the chopped vegetables to the bowl with the chicken and pour the lemon-herb dressing over the top.
Toss everything together with your hands or tongs to ensure every piece of chicken and vegetable is thoroughly coated in the seasonings.
Spread the mixture onto the prepared sheet pan in a single, even layer, ensuring nothing is overcrowded so the veggies roast rather than steam.
Roast in the center of the oven for 20 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.