Preheat your grill to medium-high heat.
In a bowl, combine olive oil, lemon juice, garlic powder, salt, and pepper.
Add chicken cubes to the marinade and let sit for at least 10 minutes.
Thread chicken onto skewers, alternating with bell pepper, onion, zucchini, and cherry tomatoes.
Brush the skewers with any remaining marinade.
Place the skewers on the grill.
Grill for 15-20 minutes, turning occasionally until chicken is cooked through.
Ensure chicken reaches an internal temperature of 165°F (75°C).
Remove from grill and let rest for a few minutes.
Serve warm with your favorite dipping sauce.