Preheat oven to 400°F (204°C).
Grease a large baking dish.
Wash and slice zucchini, tomatoes, and red onion. Dice chicken into bite-sized pieces.
In a large bowl, combine chicken with olive oil, oregano, Italian seasoning, paprika, salt, and black pepper.
Add zucchini, tomatoes, onions, and garlic to the bowl and toss gently to combine.
Transfer mixture evenly into prepared baking dish.
Sprinkle mozzarella cheese and feta cheese evenly over the top.
Bake uncovered for 25–30 minutes until chicken is fully cooked and vegetables are tender.
Garnish with fresh parsley or basil before serving.
Serve warm on its own or with rice, quinoa, or garlic bread.