Prepare the marinade by mixing olive oil, soy sauce, garlic powder, oregano, salt, and pepper in a bowl.
Add the cubed chicken to the marinade, ensuring it’s evenly coated. Let it marinate for at least 30 minutes, or up to 2 hours in the refrigerator.
While the chicken marinates, prepare the vegetables by cutting them into appropriate sized pieces, about 1-inch cubes or rounds.
Soak wooden skewers in water for 30 minutes (if using) to prevent them from burning on the grill.
Preheat the grill to medium-high heat.
Thread the marinated chicken and prepared vegetables alternately onto the skewers.
Place the skewers on the grill and cook for 10-15 minutes, turning occasionally until the chicken is fully cooked and vegetables are tender but still crisp.
Remove the skewers from the grill and let them rest for a few minutes before serving.