Preheat the oven to 425°F (220°C).
Add the garlic powder, smoked paprika, dried oregano, cumin, salt, and black pepper to a large bowl.
Pour in the olive oil and stir until the spices form a well-combined marinade.
Add the bite-size chicken pieces, chopped onion, and zucchini to the bowl.
Toss thoroughly until the chicken and vegetables are evenly coated with the seasoning mixture.
For deeper flavor, cover and marinate for 15 minutes or up to 24 hours in the refrigerator.
Transfer the seasoned chicken and vegetables to a baking dish and spread them into an even layer.
Bake uncovered at 425°F (220°C) for about 30 minutes, or until the chicken is cooked through and the vegetables are tender.
Serve this baked chicken and zucchini hot with fluffy quinoa, buttery rice, or another favorite side.